Aqueous dispersion, its production method, and its use

ABSTRACT

An aqueous dispersions including (A) at least one ethylene-based polyolefin forming a dispersed polymer phase; (B) at least one dispersing agent; and (C) water; wherein the dispersion has a pH of less than 12; and wherein the dispersed polymer phase has a volume average particle size of less than about 5 microns. In other aspects, an article or a substrate including a coating, wherein the coating was obtained from an aqueous dispersion comprising (A) at least one of an ethylene-based polyolefin and a propylene-based polyolefin; (B) at least one dispersing agent; and (C) water; wherein the dispersion had a pH of less than 12.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit, pursuant to 35 U.S.C. §120as a continuation in part application of U.S. patent application Ser.No. 10/925,693 filed Aug. 25, 2004, now U.S. Pat. No. 7,803,865, whichclaims priority to U.S. Provisional Application Ser. No. 60/497,527,filed on Aug. 25, 2003, and U.S. Provisional Application Ser. No.60/548,493, filed on Feb. 27, 2004, the disclosures of which areincorporated herein by reference in their entirety.

BACKGROUND OF DISCLOSURE

1. Field of Disclosure

Embodiments disclosed herein relate to aqueous dispersions, andcoatings, films, and articles formed therefrom. More specifically,embodiments disclosed herein relate to aqueous dispersions formed fromethylene-based and propylene-based polyolefins.

2. Background

Aqueous dispersions of a thermoplastic resin of various types are knownin the art. Aqueous dispersions, prepared using water as the dispersionmedium, have been used in a wide variety of fields and are far moreadvantageous than dispersions prepared using an organic solvent as thedispersion medium in view of flammability, working environment, handlingconvenience, and the like. For example, when an aqueous dispersion iscoated and dried on a surface of a substrate such as paper, fiber, wood,metal, or plastic molded article, the resin coating formed will providethe substrate with water resistance, oil resistance, chemicalresistance, corrosion resistance and heat sealability.

Conventional aqueous dispersions of a thermoplastic resin have beenproduced either by a process wherein a polymerizable monomer which isthe resin raw material is polymerized by emulsion polymerization in anaqueous medium in the presence of a dispersing agent, or by a processwherein a molten thermoplastic resin and an aqueous medium, andoptionally, a dispersing agent are mixed by applying shearing force. Theformer process is associated with the disadvantage of the limited numberof the polymerizable monomers that can be used, and hence, the varietyof the aqueous dispersions of the thermoplastic resin that can beproduced is limited. The former process also suffers from complicatedcontrol of the polymerization reaction as well as intricate equipment.On the other hand, the latter process is applicable to a wide variety ofresins in relatively simple equipment.

One particular application for coatings made from dispersions is inpackaging and storage container applications. To be useful, a balance ofperformance properties such as low heat seal initiation temperature, ahigh hot tack strength, a broad hot sealing window, good interlayeradhesion, and a high softening point is desirable.

The commercial importance of balanced sealant properties is wellunderstood. That is, low heat seal initiation temperatures are importantfor improved sealing speeds and reduced energy utilization. A broadsealing window is important for insuring package integrity, sealingequipment flexibility and low package leakage rates.

Good interlayer adhesion is also important for good package integrity aswell as good package or container aesthetics. High softening points ortemperatures are desired where goods are packaged at elevatedtemperatures such as in hot-fill applications. Traditionally, whenattempting to achieve balanced sealant properties, enhancement of oneparticular resin property has required some sacrifice with respect toanother important property.

For instance, with ethylene alpha-olefin polymers, low heat sealinitiation temperatures are typically achieved by increasing thecomonomer content of the resin. Conversely, high Vicat softening pointsand low levels of n-hexane extractives are typically achieved bydecreasing the comonomer content of the resin. Accordingly, lowering theheat seal initiation temperature typically results in proportionallyreduced Vicat softening temperature and proportionally increasedextractable level. U.S. Pat. No. 5,874,139, which is assigned to theassignee of the present invention and is expressly incorporated byreference in its entirety, provides a general discussion of polyolefinsin packaging applications.

Several important multilayer packaging and storage structures consist ofa polypropylene layer, particularly, a biaxially oriented polypropylenehomopolymer (BOPP) base or core layer. Often, BOPP structures utilizepolypropylene copolymers and terpolymers as sealant materials (and/oradhesive layers) to insure good interlayer adhesion to the BOPP baselayer. While polypropylene copolymers and terpolymers do indeed providegood interlayer adhesion to BOPP base layers as well as good heat sealstrength performance, these copolymers and terpolymers sometimes exhibitundesirably high heat seal initiation temperatures. For example, Table 1presents typical melting point and crystallinity values forZiegler-Natta catalyzed propylene-ethylene copolymers as a function ofthe ethylene content.

TABLE 1 Ethylene Content Melting Point Crystallinity Heat of Fusion(weight percent) (° C.) (%) (J/g) 3.8 141 50 82.8 3.9 143 — 4.6 143 —4.6 139 — 4.7 139 — 5.2 138 — 5.5 134 — 5.5 134 46 78.3 5.7 129 — 5.7133 — 5.8 135 — 5.8 134 — 5.9 134 — 5.9 133 44 72.2 6.1 132 44 71.9 6.1135 — 6.4 135 — 6.8 128 — 7.0 129 — 7.0 135 — 8.0 123 35 57.9

Other materials have also been used as sealant materials for multilayerpackaging and storage structures. However, in general, known sealantmaterials do not provide the desired overall property balance and/orprocess flexibility desired by converters and packagers.

SUMMARY OF DISCLOSURE

In one aspect the invention provides an aqueous dispersion comprising(A) at least one thermoplastic resin; (B) at least one dispersing agent;and (C) water; wherein the dispersion has a pH of less than 12. Inanother aspect the invention provides an aqueous dispersion comprising(A) at least one thermoplastic resin; (B) at least one dispersing agent;and (C) water; wherein the dispersion has a volume average particle sizeof less than about 5 μm. In some dispersions according to either aspect,the dispersing agent comprises less than about 4 percent by weight basedon the weight of the thermoplastic resin. In some dispersions having apH of 12 or less, the dispersion also has a volume average particle sizeof less than about 5 μm. Some dispersions that have a particle size ofless than about 5 μm also have a pH of less than 12. In still otherembodiments, the dispersion has a pH of less than 12, and an averageparticle size of less than about 5 μm, and wherein the dispersing agentcomprises less than about 4 percent by weight based on the weight of thethermoplastic resin.

In some dispersions the thermoplastic resin is an alpha-olefininterpolymer of ethylene with at least one comonomer selected from thegroup consisting of a C₄-C₂₀ linear, branched or cyclic diene, or anethylene vinyl compound, such as vinyl acetate, and a compoundrepresented by the formula H₂C═CHR wherein R is a C₁-C₂₀ linear,branched or cyclic alkyl group or a C₆-C₂₀ aryl group. Preferredcomonomers include propylene, 1-butene, 3-methyl-1-butene,4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-hexene, 1-octene,1-decene, and 1-dodecene. In some embodiments, the interpolymer ofethylene has a density of less than about 0.92 g/cc.

In other embodiments, the thermoplastic resin comprises an alpha-olefininterpolymer of propylene with at least one comonomer selected from thegroup consisting of ethylene, a C₄-C₂₀ linear, branched or cyclic diene,and a compound represented by the formula H₂C═CHR wherein R is a C₁-C₂₀linear, branched or cyclic alkyl group or a C₆-C₂₀ aryl group. Preferredcomonomers include ethylene, 1-butene, 3-methyl-1-butene,4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-hexene, 1-octene,1-decene, and 1-dodecene. In some embodiments, the comonomer is presentat about 5 percent by weight to about 25 percent by weight of theinterpolymer. In some embodiments, a propylene-ethylene interpolymer ispreferred.

Some interpolymers of propylene that are useful in particularembodiments are propylene-rich alpha-olefin interpolymer comprising 5 to25 percent by weight of ethylene-derived units and 95 to 75 percent byweight of propylene-derived units. In some embodiments, propylene richalpha-olefin interpolymers having (a) a melting point of less than 90°C.; a relationship of elasticity to 500% tensile modulus such that theelasticity is less than or equal to 0.935M+12, where elasticity is inpercent and M is the 500% tensile modulus in MPa; and a relationship offlexural modulus to 500% tensile modulus such that flexural modulus isless than or equal to 4.2e^(0.27M)+50, where flexural modulus is in MPaand M is the 500% tensile modulus in MPa, are preferred. In someembodiments, the propylene rich alpha-olefin interpolymer comprises 6 to20 percent by weight of ethylene-derived units and 94 to 80 percent byweight of propylene-derived units. In other embodiments, polymerscomprising 8 to 20 percent by weight of ethylene-derived units and 92 to80 percent by weight of propylene-derived units are preferred. In stillother embodiments, polymers comprising 10 to 20 percent by weight ofethylene-derived units and 90 to 80 percent by weight ofpropylene-derived units.

In other embodiments, a propylene-rich alpha-olefin interpolymer thatcomprises a copolymer of propylene and at least one comonomer selectedfrom the group consisting of ethylene and C₄ to C₂₀ alpha-olefins,wherein the copolymer has a propylene content of greater than 65 molepercent, a weight average molecular weight (Mw) of from about 15,000 toabout 200,000, a weight average molecular weight/number averagemolecular weight ratio (Mw/Mn) of from about 1.5 to about 4 ispreferred.

Some propylene-rich alpha-olefin interpolymers useful in someembodiments have a heat of fusion of less than about 80 J/g, preferablyfrom about 8 to about 80, or from about 8 to about 30 J/g as determinedby DSC.

In some embodiments, the at least one thermoplastic resin has acrystallinity of less than about 50 percent. In other embodiments, thecrystallinity ranges from about 5 percent to about 45 percent or fromabout 5 percent to about 40 percent.

Any suitable dispersing agent may be used. However, in particularembodiments, the dispersing agent may comprise at least one carboxylicacid, a salt of at least one carboxylic acid, a carboxylic acid ester,or a salt of a carboxylic acid ester. One example of a carboxylic aciduseful as a dispersing agent is a fatty acid such as montanic acid. Insome preferred embodiments, the carboxylic acid, the salt of thecarboxylic acid, or at least one carboxylic acid fragment of thecarboxylic acid ester or at least one carboxylic acid fragment of thesalt of the carboxylic acid ester has fewer than 25 carbon atoms. Inother embodiments, the carboxylic acid, the salt of the carboxylic acid,or at least one carboxylic acid fragment of the carboxylic acid ester orat least one carboxylic acid fragment of the salt of the carboxylic acidester has 12 to 25 carbon atoms. In some embodiments, carboxylic acids,salts of the carboxylic acid, at least one carboxylic acid fragment ofthe carboxylic acid ester or its salt having 15 to 25 carbon atoms arepreferred. In other embodiments, the number of carbon atoms is 25 to 60.Some preferred salts comprise a cation selected from the groupconsisting of an alkali metal cation, alkaline earth metal cation, orammonium or alkyl ammonium cation.

In still other embodiments, the dispersing agent is selected from thegroup consisting of ethylene carboxylic acid polymers and their salts,such as ethylene acrylic acid copolymers or ethylene methacrylic acidcopolymers.

In other embodiments, the dispersing agent is selected from alkyl ethercarboxylates, petroleum sulfonates, sulfonated polyoxyethylenatedalcohol, sulfated or phosphated polyoxyethylenated alcohols, polymericethylene oxide/propylene oxide/ethylene oxide dispersing agents, primaryand secondary alcohol ethoxylates, alkyl glycosides and alkylglycerides.

Combinations of any of the above-enumerated dispersing agents may alsobe used to prepare some of the aqueous dispersions disclosed herein.

Some dispersions described herein have an advantageous particle sizedistribution. In particular embodiments, the dispersion has a particlesize distribution defined as volume average particle diameter (Dv)divided by number average particle diameter (Dn) of less than or equalto about 2.0. In other embodiments, the dispersion has a particle sizedistribution of less than or equal to about 1.5.

Some dispersions described herein comprise particles having an averageparticle size of less than about 1.5 μm. In other embodiments, theaverage particle size ranges from about 0.05 μm to about 1.5 μm. Instill other embodiments, the average particle size of the dispersionranges from about 0.5 μm to about 1.5 μm.

For dispersions having a pH of less than 12, some dispersions have a pHfrom about 5 to about 11.5, preferably from about 7 to about 11, morepreferably from about 9 to about 11. The pH may be controlled by anumber of factors, including type or strength of base (dispersingagent), degree of conversion of the base to the salt form, type ofthermoplastic polymer to be dispersed, and melt kneading (e.g.,extruder) processing conditions. The pH may be adjusted either in-situ,or by converting the carboxylic acid dispersing agent to the salt form,before adding it to the thermoplastic resin and forming the dispersion.Of these, forming the salt in-situ is preferred.

Preferably, the dispersions are characterized by a solids content ofless than about 74 percent by volume. Some dispersions have a solidcontent of from about 5 percent to about 74 percent by volume. Stillother dispersions have a percent solid of less than about 70 percent byvolume, less than about 65 percent by volume, or from about 5 percent toabout 50 percent by volume.

In another aspect, embodiments disclosed herein provide a method forproducing an aqueous dispersion comprising: (1) melt kneading (A) atleast one thermoplastic resin and (B) at least one dispersing agent, toproduce a melt-kneaded product, and (2) diluting the melt-kneadedproduct, and melt kneading the resulting mixture to form the aqueousdispersion, wherein the dispersion has an average particle size of lessthan about 5 μm. Other embodiments provide a method for producing anaqueous dispersion comprising: (1) melt kneading (A) at least onethermoplastic resin, and (B) at least one dispersing agent, to produce amelt-kneaded product, and (2) diluting the melt-kneaded product, andmelt kneading the resulting mixture to form the aqueous dispersion toproduce a dispersion having a pH of less than 12. In some methodsaccording to either aspect, the dispersing agent comprises less thanabout 4 percent by weight based on the weight of the thermoplasticresin. In some methods that provide a dispersion having a pH of 12 orless, the dispersion also has a volume average particle size of lessthan about 5 μm. Some dispersions that have a particle size of less thanabout 5 μm also have a pH of less than 12. Embodiments of the methodsdescribed herein use the thermoplastic resins and dispersing agentsdescribed above. And in some embodiments, the methods providedispersions having one or more of the properties described above.

In another aspect, embodiments disclosed herein provide an aqueousdispersion comprising: (A) at least one propylene-rich alpha-olefininterpolymer; (B) at least one dispersing agent; and (C) water. Onepreferred alpha-olefin is ethylene, preferably present in an amount offrom about 5 percent to about 25 percent by weight. In some embodiments,the propylene-rich alpha-olefin interpolymer is characterized as havingan isotactic triad (mm) measured by ¹³C NMR of greater than about 0.85.Some such propylene-rich alpha-olefin interpolymers comprise 5 to 25percent by weight of ethylene-derived units and 95 to 75 percent byweight of propylene-derived units. Additionally, some propylene-richalpha-olefin interpolymers have (a) a melting point of less than 90° C.;(b) a relationship of elasticity to 500% tensile modulus such that theelasticity is less than or equal to 0.935M+12, where elasticity is inpercent and M is the 500% tensile modulus in MPa; and (c) a relationshipof flexural modulus to 500% tensile modulus such that flexural modulusis less than or equal to 4.2e^(0.27M)+50, where flexural modulus is inMPa and M is the 500% tensile modulus in MPa. In some embodiments, thepropylene-rich alpha-olefin interpolymer comprises 6 to 20 percent byweight of ethylene-derived units and 94 to 80 percent by weight ofpropylene-derived units. In other embodiments, polymers comprising 8 to20 percent by weight of ethylene-derived units and 92 to 80 percent byweight of propylene-derived units are preferred. In still otherembodiments, polymers comprising 10 to 20 percent by weight ofethylene-derived units and 90 to 80 percent by weight ofpropylene-derived units.

Some thermoplastic resins or propylene-rich alpha-olefin interpolymersused in this aspect have a heat of fusion of less than about 80 J/g,preferably from about 8 to about 80, or more preferably from about 8 toabout 30 J/g as determined by DSC.

In some embodiments, the propylene-rich alpha-olefin interpolymer has acrystallinity of less than about 50 percent. In other embodiments, thecrystallinity ranges from about 5 percent to about 45 percent or fromabout 5 percent to about 40 percent.

In still other embodiments, the propylene-rich interpolymer has aflexural modulus, measured in accordance with ASTM D-790-97, of lessthan about 50 kpsi, preferably less than about 40 kpsi, more preferablyless than about 30 kpsi. In some dispersions, polymers having a lowervalue for the flexural modulus are preferred. For example, some polymershave a flexural modulus of about 2 to about 15 kpsi, particularly about4 to about 10 kpsi.

Propylene-rich interpolymers or thermoplastic resins with a meltingpoint of less than about 140° C., preferably less than about 130° C.,more preferably less than about 120° C. are used. In some preferredembodiments, the propylene-rich interpolymer or thermoplastic resin hasa melting point of less than about 90° C. In other embodiments, thepropylene-rich interpolymer may have a melting point from about 25° C.to about 105° C.

Any suitable dispersing agent may be used in various embodiments.However, in particular embodiments, the dispersing agent may comprise atleast one carboxylic acid, a salt of at least one carboxylic acid, acarboxylic acid ester, or a salt of a carboxylic acid ester. In somepreferred embodiments, the carboxylic acid, the salt of the carboxylicacid, or at least one carboxylic acid fragment of the carboxylic acidester or its salt has fewer than 25 carbon atoms. In other embodiments,such moieties have 12 to 25 carbon atoms. In some embodiments, 15 to 25carbon atoms are preferred. In other embodiments, the dispersing agentcomprises at least one carboxylic acid, the salt of the at least onecarboxylic acid, at least one carboxylic acid fragment of the carboxylicacid ester or its salt that has 25 to 60 carbon atoms. Some preferredsalts comprise a cation selected from the group consisting of an alkalimetal cation, alkaline earth metal cation, or ammonium or alkyl ammoniumcation.

In still other embodiments, the dispersing agent is selected from thegroup consisting of ethylene acid polymers such as ethylene acrylic acidcopolymers or ethylene methacrylic acid copolymers.

In other embodiments, the dispersing agent is selected from alkyl ethercarboxylates, petroleum sulfonates, sulfonated polyoxyethylenatedalcohol, sulfated or phosphated polyoxyethylenated alcohols, polymericethylene oxide/propylene oxide/ethylene oxide dispersing agents, primaryand secondary alcohol ethoxylates, alkyl glycosides and alkylglycerides.

Combinations of any of the above-enumerated dispersing agents can alsobe used to prepare some aqueous dispersions.

Some dispersions described herein have an advantageous particle sizedistribution. In particular embodiments, the dispersion has a particlesize distribution defined as volume average particle diameter (Dv)divided by number average particle diameter (Dn) of less than or equalto about 2.0. In other embodiments, the dispersion has a particle sizedistribution of less than or equal to about 1.5.

Some dispersions described herein comprise particles having a volumeaverage particle size of less than about 1.5 μm. In other embodiments,the average particle size ranges from about 0.05 μm to about 1.5 μm. Instill other embodiments, the average particle size of the dispersionranges from about 0.5 μm to about 1.5 μm.

For dispersions having a pH of less than 12, some dispersions have a pHof from about 5 to about 11.5, preferably from about 7 to about 11, morepreferably from about 9 to about 11.

Preferably, the dispersions are characterized by a percent solidscontent of less than about 74 percent by volume. Some dispersions have apercent solid of from about 5 percent to about 74 percent by volume.Still other dispersions have a percent solid of less than about 70percent by volume, less than about 65 percent by volume, or from about 5percent to about 50 percent by volume.

In another aspect, embodiments provide a method for producing an aqueousdispersion comprising: (1) melt kneading (A) at least one at least onepropylene-rich alpha-olefin interpolymer and (B) at least one dispersingagent to form a melt-kneaded product; and (2) diluting the melt-kneadedproduct, and melt kneading the resulting mixture to form the aqueousdispersion. In particular embodiments, the method includes diluting themelt kneaded product to provide a dispersion having a pH of less than12. Some methods provide a dispersion with an average particle size ofless than about 5 μm. In still other embodiments, the method provides adispersion that comprises less than 4 percent by weight of thedispersing agent based on the weight of the polymer. Embodiments of themethods use the thermoplastic resins and dispersing agents describedabove. And in some embodiments, the methods provide dispersions havingon or more of the properties described above.

In still another aspect embodiments of the invention provide an aqueousdispersion comprising: (A) at least one thermoplastic resin; (B) atleast one dispersing agent; and (C) water; wherein the thermoplasticresin comprises a propylene-rich alpha-olefin interpolymer comprising 5to 25 percent by weight of ethylene-derived units and 95 to 75 percentby weight of propylene-derived units, the copolymer having: (a) amelting point of less than 90° C.; (b) a relationship of elasticity to500% tensile modulus such that the elasticity is less than or equal to0.935M+12, where elasticity is in percent and M is the 500% tensilemodulus in MPa; and (c) a relationship of flexural modulus to 500%tensile modulus such that flexural modulus is less than or equal to4.2e^(0.27M)+50, where flexural modulus is in MPa and M is the 500%tensile modulus in MPa.

In another aspect of the invention, some dispersions are suitable formaking various articles. Some such articles include coatings, foams, andfroths as well as decorative articles.

In another aspect of the invention, some dispersions include (A) atleast one ethylene-based polyolefin forming a dispersed polymer phase;(B) at least one dispersing agent; and (C) water; wherein the dispersionhas a pH of less than 12; wherein the dispersed polymer phase has avolume average particle size of less than about 5 microns; and whereinthe ethylene-based polyolefin comprises an interpolymer of ethylene withat least one comonomer selected from the group consisting of a C₄-C₂₀linear, branched or cyclic diene, vinyl acetate, and a compoundrepresented by the formula H₁C═CHR wherein R is a C₁-C₂₀ linear,branched or cyclic alkyl group or a C₆-C₂₀ aryl group.

In another aspect, a substrate may include a coating, wherein thecoating was obtained from an aqueous dispersion comprising (A) at leastone of an ethylene-based polyolefin and a propylene-based polyolefin;(B) at least one dispersing agent; and (C) water; wherein the dispersionhad a pH of less than 12.

In yet another aspect, articles may include a substrate having acoating, wherein the coating was obtained from: an aqueous dispersioncomprising (A) at least one of an ethylene-based polyolefin and apropylene-based polyolefin; (B) at least one dispersing agent; and (C)water; wherein the dispersion had a pH of less than 12

Other aspects and advantages of the invention will be apparent from thefollowing description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic representation of a typical melt-extrusionapparatus used to prepare embodiments of the invention.

FIG. 2 is a flowchart showing a method in accordance with an embodimentof the present invention.

DETAILED DESCRIPTION

In the following description, all numbers disclosed herein areapproximate values, regardless whether the word “about” or “approximate”is used in connection therewith. They may vary by 1 percent, 2 percent,5 percent, and sometimes, 10 to 20 percent. Whenever a numerical rangewith a lower limit, R_(L) and an upper limit, R_(U), is disclosed, anynumber falling within the range is specifically disclosed. Inparticular, the following numbers within the range are specificallydisclosed: R=R_(L)+k*(R_(U)−R_(L)), wherein k is a variable ranging from1 percent to 100 percent with a 1 percent increment, i.e., k is 1percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent,51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98percent, 99 percent, or 100 percent. Moreover, any numerical rangedefined by two R numbers as defined in the above is also specificallydisclosed.

Embodiments disclosed herein relate to the dispersions outlined aboveand discussed in detail below. In addition, embodiments disclosed hereinalso relate to films and other products formed from such dispersions. Inparticular embodiments, dispersions made according to the methodsdiscussed herein are applied to a substrate, which may form a heatsealable layer.

In addition, the present inventors have discovered that, by usingdispersions made with particular polyolefin polymers (which may besingle component polymer, or polymer blends), a heat sealable layer maybe formed that has a heat seal initiation temperature of 80° C. orbelow. In other embodiments, the heat seal initiation temperature may be75° C. or below. In other embodiments, the heat seal initiationtemperature may be 70° C. or below. In other embodiments, the heat sealinitiation temperature may be 65° C. or below.

The thermoplastic resin (A) included in embodiments of the aqueousdispersion is a resin that is not readily dispersible in water byitself. In some embodiments the thermoplastic resin is present in thedispersion in an amount from greater than 0 percent by weight to lessthan about 96 percent by weight. In certain embodiments, the resin ispresent in an amount from about 35 to about 65 percent by weight of thedispersion. The term “resin” used herein should be construed to includesynthetic polymers or chemically modified natural resins such as but notlimited to thermoplastic materials such as polyvinyl chloride,polystyrene, and polyethylene and thermosetting materials such aspolyesters, epoxies, and silicones that are used with fillers,stabilizers, pigments, and other components to form plastics. The termresin as used herein includes elastomers and is understood to includeblends of olefin polymers. In some embodiments, the thermoplastic resinis a semicrystalline resin. The term “semi-crystalline” is intended toidentify those resins that possess at least one endotherm when subjectedto standard differential scanning calorimetry (DSC) evaluation. Somesemi-crystalline polymers exhibit a DSC endotherm that exhibits arelatively gentle slope as the scanning temperature is increased pastthe final endotherm maximum. This reflects a polymer of broad meltingrange rather than a polymer having what is generally considered to be asharp melting point. Some polymers useful in the dispersions disclosedherein have a single melting point while other polymers have more thanone melting point. In some polymers, one or more of the melting pointsmay be sharp such that all or a portion of the polymer melts over afairly narrow temperature range, such as a few degrees centigrade. Inother embodiments, the polymer may exhibit broad melting characteristicsover a range of about 20° C. In yet other embodiments, the polymer mayexhibit broad melting characteristics over a range of greater than 50°C.

Examples of the thermoplastic resin (A) which may be used includehomopolymers and copolymers (including elastomers) of an alpha-olefinsuch as ethylene, propylene, 1-butene, 3-methyl-1-butene,4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-hexene, 1-octene,1-decene, and 1-dodecene as typically represented by polyethylene,polypropylene, poly-1-butene, poly-3-methyl-1-butene,poly-3-methyl-1-pentene, poly-4-methyl-1-pentene, ethylene-propylenecopolymer, ethylene-1-butene copolymer, and propylene-1-butenecopolymer; copolymers (including elastomers) of an alpha-olefin with aconjugated or non-conjugated diene as typically represented byethylene-butadiene copolymer and ethylene-ethylidene norbornenecopolymer; and polyolefins (including elastomers) such as copolymers oftwo or more alpha-olefins with a conjugated or non-conjugated diene astypically represented by ethylene-propylene-butadiene copolymer,ethylene-propylene-dicyclopentadiene copolymer,ethylene-propylene-1,5-hexadiene copolymer, andethylene-propylene-ethylidene norbornene copolymer; ethylene-vinylcompound copolymers such as ethylene-vinyl acetate copolymer,ethylene-vinyl alcohol copolymer, ethylene-vinyl chloride copolymer,ethylene acrylic acid or ethylene-(meth)acrylic acid copolymers, andethylene-(meth)acrylate copolymer; styrenic copolymers (includingelastomers) such as polystyrene, ABS, acrylonitrile-styrene copolymer,α-methylstyrene-styrene copolymer; and styrene block copolymers(including elastomers) such as styrene-butadiene copolymer and hydratethereof, and styrene-isoprene-styrene tri-block copolymer; polyvinylcompounds such as polyvinyl chloride, polyvinylidene chloride, vinylchloride-vinylidene chloride copolymer, polymethyl acrylate, andpolymethyl methacrylate; polyamides such as nylon 6, nylon 6,6, andnylon 12; thermoplastic polyesters such as polyethylene terephthalateand polybutylene terephthalate; polycarbonate, polyphenylene oxide, andthe like. These resins may be used either alone or in combinations oftwo or more.

In particular embodiments, polyolefins such as polypropylene,polyethylene, and copolymers thereof and blends thereof, as well asethylene-propylene-diene terpolymers. In some embodiments, preferredolefinic polymers include homogeneous polymers described in U.S. Pat.No. 3,645,992 by Elston; high density polyethylene (HDPE) as describedin U.S. Pat. No. 4,076,698 to Anderson; heterogeneously branched linearlow density polyethylene (LLDPE); heterogeneously branched ultra lowlinear density (ULDPE); homogeneously branched, linearethylene/alpha-olefin copolymers; homogeneously branched, substantiallylinear ethylene/alpha-olefin polymers which can be prepared, forexample, by a process disclosed in U.S. Pat. Nos. 5,272,236 and5,278,272, the disclosure of which process is incorporated herein byreference; and high pressure, free radical polymerized ethylene polymersand copolymers such as low density polyethylene (LDPE), ethylene-acrylicacid (EAA) and Ethylene-methacrylic acid copolymers such as for examplethose available under the tradenames PRIMACOR™, NUCREL™, and ESCOR™ anddescribed in U.S. Pat. Nos. 4,599,392, 4,988,781, and 5,938,4373, eachof which is incorporated herein by reference in its entirety, andethylene-vinyl acetate (EVA) copolymers. Polymer compositions describedin U.S. Pat. No. 6,538,070, 6,566,446, 5,869,575, 6,448,341, 5,677,383,6,316,549, 6,111,023, or 5,844,045, each of which is incorporated hereinby reference in its entirety, are also suitable in some embodiments. Ofcourse, blends of polymers can be used as well. In some embodiments theblends include two different Ziegler-Natta polymers. In otherembodiments, the blends may include blends of a Ziegler-Natta and ametallocene polymer. In still other embodiments, the thermoplastic resinused herein is a blend of two different metallocene polymers.

In some particular embodiments, the thermoplastic resin is apropylene-based copolymer or interpolymer. In some embodiments thepropylene/ethylene copolymer or interpolymer is characterized as havingsubstantially isotactic propylene sequences. The term “substantiallyisotactic propylene sequences” and similar terms mean that the sequenceshave an isotactic triad (mm) measured by ¹³C NMR of greater than about0.85, preferably greater than about 0.90, more preferably greater thanabout 0.92 and most preferably greater than about 0.93. Isotactic triadsare well-known in the art and are described in, for example, U.S. Pat.No. 5,504,172 and WO 00/01745, which refer to the isotactic sequence interms of a triad unit in the copolymer molecular chain determined by ¹³CNMR spectra. NMR spectra are determined as described below. Preferably,when the aqueous dispersions comprise a propylene/ethylene interpolymer,the ethylene is present in an amount of from about 5 percent to about 25percent (by weight).

¹³C NMR spectroscopy is one of a number of techniques known in the artof measuring comonomer incorporation into a polymer and measuringisotactic triad levels in propylene-based copolymers. An example of thistechnique is described for the determination of comonomer content forethylene/α-olefin copolymers in Randall (Journal of MacromolecularScience, Reviews in Macromolecular Chemistry and Physics, C29 (2 & 3),201-317 (1989)). The basic procedure for determining the comonomercontent of an olefin interpolymer involves obtaining the ¹³C NMRspectrum under conditions where the intensity of the peaks correspondingto the different carbons in the sample is directly proportional to thetotal number of contributing nuclei in the sample. Methods for ensuringthis proportionality are known in the art and involve allowance forsufficient time for relaxation after a pulse, the use ofgated-decoupling techniques, relaxation agents, and the like. Therelative intensity of a peak or group of peaks is obtained in practicefrom its computer-generated integral. After obtaining the spectrum andintegrating the peaks, those peaks associated with the comonomer areassigned. This assignment can be made by reference to known spectra orliterature, or by synthesis and analysis of model compounds, or by theuse of isotopically labeled comonomer. The mole percent comonomer can bedetermined by the ratio of the integrals corresponding to the number ofmoles of comonomer to the integrals corresponding to the number of molesof all of the monomers in the interpolymer, as described in Randall, forexample.

The data may be collected using a Varian UNITY Plus 400 MHz NMRspectrometer, corresponding to a ¹³C resonance frequency of 100.4 MHz.Acquisition parameters are selected to ensure quantitative ¹³C dataacquisition in the presence of the relaxation agent. The data isacquired using gated 1H decoupling, 4000 transients per data file, a 7sec pulse repetition delay, spectral width of 24,200 Hz and a file sizeof 32K data points, with the probe head heated to 130° C. The sample isprepared by adding approximately 3 mL of a 50/50 mixture oftetrachloroethane-d2/orthodichlorobenzene that is 0.025M in chromiumacetylacetonate (relaxation agent) to 0.4 g sample in a 10 mm NMR tube.The headspace of the tube is purged of oxygen by displacement with purenitrogen. The sample is dissolved and homogenized by heating the tubeand its contents to 150° C. with periodic refluxing initiated by a heatgun.

Preferably, the propylene/ethylene interpolymer has a crystallinity ofless than about 50 percent and a flexural modulus, measured inaccordance with ASTM D-790-97, of less than about 50 kpsi, preferablyless than about 40 kpsi, and especially less than about 30 kpsi.Preferably, the propylene/ethylene interpolymer has a melting point ofless than about 140° C., preferably less than about 130° C., morepreferably less than about 120° C., especially less than about 90° C.The propylene/ethylene interpolymers used in the dispersions alsopreferably have a heat of fusion of less than 80 J/gm, more preferablyless than about 75 J/gm, more preferably less than about 50 J/gm, andcan be as low as about 8 J/gm, or as low as 4 J/gm.

In some preferred dispersions, the propylene-based copolymer comprises apropylene-ethylene copolymer made using a non-metallocene,metal-centered, heteroaryl ligand catalyst as described in U.S. Pat. No.6,960,635, which is incorporated by reference herein in its entirety forits teachings regarding such catalysts. The propylene-ethylenecopolymers made with such non-metallocene, metal-centered, heteroarylligand catalyst exhibit a unique regio-error. The regio-error isidentified by ¹³C NMR peaks corresponding at about 14.6 and about 15.7ppm, which are believed to be the result of stereo-selective2,1-insertion errors of propylene units into the growing polymer chain.In this particularly preferred aspect, these peaks are of about equalintensity, and they typically represent about 0.02 to about 7 molepercent of the propylene insertions into the homopolymer or copolymerchain.

In some aspects, the propylene-based copolymer has a molecular weightdistribution (MWD), defined as weight average molecular weight dividedby number average molecular weight (Mw/Mn) of about 4 or less, and canbe as low as about 1.5.

Molecular weight distribution of the polymers is determined using gelpermeation chromatography (GPC) on a Polymer Laboratories PL-GPC-220high temperature chromatographic unit equipped with four linear mixedbed columns (Polymer Laboratories (20-micron particle size)). The oventemperature is at 160° C. with the autosampler hot zone at 160° C. andthe warm zone at 145° C. The solvent is 1,2,4-trichlorobenzenecontaining 200 ppm 2,6-di-t-butyl-4-methylphenol. The flow rate is 1.0milliliter/minute and the injection size is 100 microliters. About 0.2percent by weight solutions of the samples are prepared for injection bydissolving the sample in nitrogen purged 1,2,4-trichlorobenzenecontaining 200 ppm 2,6-di-t-butyl-4-methylphenol for 2.5 hours at 160°C. with gentle mixing.

The molecular weight determination is deduced by using ten narrowmolecular weight distribution polystyrene standards (from PolymerLaboratories, EasiCal PSI ranging from 580 to 7,500,000 g/mole) inconjunction with their elution volumes. The equivalentpropylene-ethylene copolymer molecular weights are determined by usingappropriate Mark-Houwink coefficients for polypropylene (as described byTh. G. Scholte, N. L. J. Meijerink, H. M. Schoffeleers, and A. M. G.Brands, J. Appl. Polym. Sci., 29, 3763-3782 (1984)) and polystyrene (asdescribed by E. P. Otocka, R. J. Roe, N. Y. Hellman, P. M. Muglia,Macromolecules, 4, 507 (1971)) in the Mark-Houwink equation: {N}=KMa,where K_(pp)=1.90E-04, a_(pp)=0.725 and K_(pa)=1.26E-04, a_(ps)=0.702.

In one embodiment, the thermoplastic resins utilized in embodimentsdisclosed herein are characterized by a DSC curve with a Tme thatremains essentially the same and a Tmax that decreases as the amount ofunsaturated comonomer in the copolymer is increased. Tme refers to thetemperature at which the melting ends and Tmax refers to the peakmelting temperature, both as determined by one of ordinary skill in theart from DSC analysis using data from the final heating step. For suchpolymers, DSC analysis can be determined using a model Q1000 DSC from TAInstruments, Inc., which is calibrated using indium and deionized water.

In some other embodiments, thermoplastic polymer compositions disclosedin U.S. Pat. No. 6,525,157, incorporated by reference in its entirety.The polymers described therein comprise a majority of propylene with aminor amount of ethylene. These polymer compositions include a linear,single homogeneous macromolecular copolymer structure. These polymershave limited crystallinity due to adjacent isotactic propylene units andhave a melting point as described below. They are generally devoid ofany substantial intermolecular heterogeneity in tacticity and comonomercomposition, and are substantially free of diene. They are also devoidof any substantial heterogeneity in intramolecular compositiondistribution.

In some embodiments of the dispersions described herein, the copolymerincludes from a lower limit of 5 percent or 6 percent or 8 percent or 10percent by weight ethylene-derived units to an upper limit of 20 percentor 25 percent by weight ethylene-derived units. These embodiments alsowill include propylene-derived units present in the copolymer in therange of from a lower limit of 75 percent or 80 percent by weight to anupper limit of 95 percent or 94 percent or 92 percent or 90 percent byweight. These percentages by weight are based on the total weight of thepropylene and ethylene-derived units; i.e., based on the sum of weightpercent propylene-derived units and weight percent ethylene-derivedunits being 100%. Within these ranges, these copolymers are mildlycrystalline as measured by differential scanning calorimetry (DSC), andare exceptionally soft, while still retaining substantial tensilestrength and elasticity. Elasticity, as defined in detail herein, is adimensional recovery from elongation for these copolymers. At ethylenecompositions lower than the above limits for the copolymer, suchpolymers are generally crystalline, similar to crystalline isotacticpolypropylene, and while having excellent tensile strength, they do nothave the favorable softness and elasticity. At ethylene compositionshigher than the above limits for the copolymer component, the copolymeris substantially amorphous. While such a material of higher ethylenecomposition may be soft, these compositions are weak in tensile strengthand poor in elasticity. In summary, such copolymers of embodiments ofour invention exhibit the softness, tensile strength and elasticitycharacteristic of vulcanized rubbers, without vulcanization.

Propylene and ethylene are the monomers that can be used to make thecopolymers of embodiments of our invention, but optionally, ethylene canbe replaced or added to in such polymers with a C₄ to C₂₀ alpha-olefin,such as, for example, 1-butene, 4-methyl-1-pentene, 1-hexene, or1-octene.

In some embodiments of the present invention the copolymers aresubstantially free of diene-derived units. Dienes are non-conjugateddi-olefins which may be incorporated in polymers to facilitate chemicalcrosslinking reactions. “Substantially free of diene” is defined to beless than 1 percent diene, or less than 0.5 percent diene, or less than0.1 percent diene, or less than 0.05 percent diene, or equal to 0percent. All of these percentages are by weight in the copolymer. Thepresence or absence of diene can be conventionally determined byinfrared techniques well known to those skilled in the art.

Sources of diene include diene monomer added to the polymerization ofethylene and propylene, or use of diene in catalysts. No matter thesource of such dienes, the above outlined limits on their inclusion inthe copolymer are contemplated. Conjugated diene-containing metallocenecatalysts have been suggested for the formation of copolymers ofolefins. However, polymers made from such catalysts will incorporate thediene from the catalyst, consistent with the incorporation of othermonomers in the polymerization.

In some embodiments, a thermoplastic resin is included having a weightaverage molecular weight (Mw) from 15,000 to 5,000,000, or from 20,000to 1,000,000, and a molecular weight distribution Mw/Mn (sometimesreferred to as a “polydispersity index” (PDI)) ranging from a lowerlimit of 1.01, 1.5 or 1.8 to an upper limit of 40 or 20 or 10 or 5 or 3.In other embodiments the Mw may range from 10,000 to 300,000 or from100,000 to 250,000.

In the measurement of properties ascribed to some propylene-richpolymers of some dispersions, there is a substantial absence of asecondary or tertiary polymer or polymers to form a blend. By“substantial absence” we intend less than 10 percent, or less than 5percent, or less than 2.5 percent, or less than 1 percent, or 0 percent,by weight.

Another measure of molecular weight typically used for polyethylenepolymers is the melt index of the polymer, also called 12. The meltindex is indirectly proportional to the molecular weight, although therelationship is not linear. For polyethylene the melt index is measuredaccording to ASTM D-1238, condition 190° C./2.16 kg). Typicalthermoplastic resins useful in embodiments of the invention have an 12in the range from 0.001 to 1000 g/10 min. In some embodiments, thethermoplastic resin (A) has an 12 from 0.5 to 500 g/10 min. Otherembodiments include a thermoplastic resin with an 12 from 1 to 300 g/10min. The selection of suitable 12 for the thermoplastic resin should beselected in view of the ease of melt kneadability and physicalproperties of the coating formed.

Melt flow rate (MFR) is another way of measuring the molecular weight ofpolypropylene polymers. Like melt index, MFR is indirectly proportionalto the molecular weight, although the relationship is not linear. MFR istypically measured according to ASTM D-1238, condition 230° C./2.16 kg).Typical thermoplastic resins useful in embodiments of the invention havean MFR less than about 250 g/10 min. In some embodiments, thethermoplastic resin (A) has an MFR from about 1 to about 200 g/10 min.Other embodiments include a thermoplastic resin with an MFR from 5 to100 g/10 min.

In other selected embodiments, the thermoplastic resin may includeolefin block copolymers (e.g., ethylene multi-block copolymers) such asthose described in International Publication No. WO2005/090427 and U.S.patent application Ser. No. 11/376,835. The term “multi-block copolymer”refers to a polymer comprising two or more chemically distinct regionsor segments (referred to as “blocks”) preferably joined in a linearmanner, that is, a polymer comprising chemically differentiated unitswhich are joined end-to-end with respect to polymerized ethylenicfunctionality, rather than in pendent or grafted fashion. In certainembodiments, the blocks differ in the amount or type of comonomerincorporated therein, the density, the amount of crystallinity, thecrystallite size attributable to a polymer of such composition, the typeor degree of tacticity (isotactic or syndiotactic), regio-regularity orregio-irregularity, the amount of branching, including long chainbranching or hyper-branching, the homogeneity, or any other chemical orphysical property. Such olefin block copolymers may be anethylene/α-olefin interpolymer characterized by:

-   -   (a) having a Mw/Mn from about 1.7 to about 3.5, at least one        melting point, Tm, in degrees Celsius, and a density, d, in        grams/cubic centimeter, wherein the numerical values of Tm and d        corresponding to the relationship:        Tm>−2002.9+4538.5(d)−2422.2(d)²; or    -   (b) having a Mw/Mn from about 1.7 to about 3.5, a heat of        fusion, ΔH in J/g, and a delta quantity, ΔT, in degrees Celsius        defined as the temperature difference between the tallest DSC        peak and the tallest CRYSTAF peak, wherein the numerical values        of ΔT and ΔH having the following relationships:        ΔT>−0.1299(ΔH)+62.81 for ΔH greater than zero and up to 130 J/g,        ΔT≧48° C. for ΔH greater than 130 J/g,        -   wherein the CRYSTAF peak being determined using at least 5            percent of the cumulative polymer, and if less than 5            percent of the polymer having an identifiable CRYSTAF peak,            then the CRYSTAF temperature being 30° C.; or    -   (c) having an elastic recovery, Re, in percent at 300 percent        strain and 1 cycle measured with a compression-molded film of        the ethylene/α-olefin interpolymer, and having a density, d, in        grams/cubic centimeter, wherein the numerical values of Re and d        satisfying the following relationship when ethylene/α-olefin        interpolymer being substantially free of a cross-linked phase:        Re>1481−1629(d); or    -   (d) having a molecular fraction which elutes between 40° C. and        130° C. when fractionated using TREF, characterized in that the        fraction having a molar comonomer content of at least 5 percent        higher than that of a comparable random ethylene interpolymer        fraction eluting between the same temperatures, wherein said        comparable random ethylene interpolymer having the same        comonomer(s) and having a melt index, density, and molar        comonomer content (based on the whole polymer) within 10 percent        of that of the ethylene/α-olefin interpolymer; or    -   (e) having a storage modulus at 25° C., G′(25° C.), and a        storage modulus at 100° C., G′(100° C.), wherein the ratio of        G′(25° C.) to G′(100° C.) being in the range of about 1:1 to        about 9:1.

The ethylene/α-olefin interpolymer may be an ethylene/α-olefininterpolymer:

-   -   (a) having a molecular fraction which elutes between 40° C. and        130° C. when fractionated using TREF, characterized in that the        fraction having a block index of at least 0.5 and up to about 1        and a molecular weight distribution, Mw/Mn, greater than about        1.3; or    -   (b) having an average block index greater than zero and up to        about 1.0 and a molecular weight distribution, Mw/Mn, greater        than about 1.3.

The above described characterizations of the olefin block copolymers maybe determined by the following test methods.

Standard CRYSTAF Method

Branching distributions may be determined by crystallization analysisfractionation (CRYSTAF) using a CRYSTAF 200 unit commercially availablefrom PolymerChar, Valencia, Spain. The samples are dissolved in 1,2,4trichlorobenzene at 160° C. (0.66 mg/mL) for 1 hr and stabilized at 95°C. for 45 minutes. The sampling temperatures range from 95° C. to 30° C.at a cooling rate of 0.2° C./min. An infrared detector is used tomeasure the polymer solution concentrations. The cumulative solubleconcentration is measured as the polymer crystallizes while thetemperature is decreased. The analytical derivative of the cumulativeprofile reflects the short chain branching distribution of the polymer.

The CRYSTAF peak temperature and area are identified by the peakanalysis module included in the CRYSTAF Software (Version 2001.b,PolymerChar, Valencia, Spain). The CRYSTAF peak finding routineidentifies a peak temperature as a maximum in the dW/dT curve and thearea between the largest positive inflections on either side of theidentified peak in the derivative curve. To calculate the CRYSTAF curve,the preferred processing parameters are with a temperature limit of 70°C. and with smoothing parameters above the temperature limit of 0.1, andbelow the temperature limit of 0.3.

Flexural/Secant Modulus/Storage Modulus

Samples are compression molded using ASTM D 1928. Flexural and 2-percentsecant moduli are measured according to ASTM D-790. Storage modulus ismeasured according to ASTM D 5026-01 or equivalent techniques.

DSC Standard Method

Differential Scanning Calorimetry results may be determined using a TAImodel Q1000 DSC equipped with an RCS cooling accessory and anautosampler. A nitrogen purge gas flow of 50 ml/min is used. The sampleis pressed into a thin film and melted in the press at about 175° C. andthen air-cooled to room temperature (25° C.). 3-10 mg of material isthen cut into a 6 mm diameter disk, accurately weighed, placed in alight aluminum pan (about 50 mg), and then crimped shut. The thermalbehavior of the sample is investigated with the following temperatureprofile. The sample is rapidly heated to 180° C. and held isothermal for3 minutes in order to remove any previous thermal history. The sample isthen cooled to −40° C. at 10° C./min cooling rate and held at −40° C.for 3 minutes. The sample is then heated to 150° C. at 10° C./minheating rate. The cooling and second heating curves are recorded.

The DSC melting peak is measured as the maximum in heat flow rate (W/g)with respect to the linear baseline drawn between −30° C. and end ofmelting. The heat of fusion is measured as the area under the meltingcurve between −30° C. and the end of melting using a linear baseline.

The DSC is calibrated as follows. First, a baseline is obtained byrunning a DSC from −90° C. without any sample in the aluminum DSC pan.Then 7 milligrams of a fresh indium sample is analyzed by heating thesample to 180° C., cooling the sample to 140° C. at a cooling rate of10° C./min followed by keeping the sample isothermally at 140° C. for 1minute, followed by heating the sample from 140° C. to 180° C. at aheating rate of 10° C./min. The heat of fusion and the onset of meltingof the indium sample are determined and checked to be within 0.5° C.from 156.6° C. for the onset of melting and within 0.5 J/g from 28.71J/g for the of fusion. Then deionized water is analyzed by cooling asmall drop of fresh sample in the DSC pan from 25° C. to −30° C. at acooling rate of 10° C./min. The sample is kept isothermally at −30° C.for 2 minutes and heated to 30° C. at a heating rate of 10° C./min. Theonset of melting is determined and checked to be within 0.5° C. from 0°C.

GPC Method

The gel permeation chromatographic (GPC) system may include either aPolymer Laboratories Model PL-210 or a Polymer Laboratories Model PL-220instrument. The column and carousel compartments are operated at 140° C.Three Polymer Laboratories 10-micron Mixed-B columns are used. Thesolvent is 1,2,4-trichlorobenzene. The samples are prepared at aconcentration of 0.1 grams of polymer in 50 milliliters of solventcontaining 200 ppm of butylated hydroxytoluene (BHT). Samples areprepared by agitating lightly for 2 hours at 160° C. The injectionvolume used is 100 microliters and the flow rate is 1.0 ml/min.

Calibration of the GPC column set is performed with 21 narrow molecularweight distribution polystyrene standards with molecular weights rangingfrom 580 to 8,400,000, arranged in 6 “cocktail” mixtures with at least adecade of separation between individual molecular weights. The standardsare purchased from Polymer Laboratories (Shropshire, UK). Thepolystyrene standards are prepared at 0.025 grams in 50 milliliters ofsolvent for molecular weights equal to or greater than 1,000,000, and0.05 grams in 50 milliliters of solvent for molecular weights less than1,000,000. The polystyrene standards are dissolved at 80° C. with gentleagitation for 30 minutes. The narrow standards mixtures are run firstand in order of decreasing highest molecular weight component tominimize degradation. The polystyrene standard peak molecular weightsare converted to polyethylene molecular weights using the followingequation (as described in Williams and Ward, J. Polym. Sci., Polym.Let., 6, 621 (1968)): M_(polyethylene)=0.431 (M_(polystyrene)).

Polyethylene equivalent molecular weight calculations are performedusing Viscotek TriSEC software Version 3.0.

ATREF

Analytical temperature rising elution fractionation (ATREF) analysis isconducted according to the method described in U.S. Pat. No. 4,798,081and Wilde, L.; Ryle, T. R.; Knobeloch, D. C.; Peat, I. R.; Determinationof Branching Distributions in Polyethylene and Ethylene Copolymers, J.Polym. Sci., 20, 441-455 (1982), both of which are incorporated byreference herein in their entirety. The composition to be analyzed isdissolved in trichlorobenzene and allowed to crystallize in a columncontaining an inert support (stainless steel shot) by slowly reducingthe temperature to 20° C. at a cooling rate of 0.1° C./min. The columnis equipped with an infrared detector. An ATREF chromatogram curve isthen generated by eluting the crystallized polymer sample from thecolumn by slowly increasing the temperature of the eluting solvent(trichlorobenzene) from 20° C. to 120° C. at a rate of 1.5° C./min.

¹³C NMR Analysis

The samples are prepared for NMR analyses by adding approximately 3 g ofa 50/50 mixture of tetrachloroethane-d²/orthodichlorobenzene to 0.4 gpolymer sample in a 10 mm NMR tube. The samples are dissolved andhomogenized by heating the tube and its contents to 150° C. The data arecollected using a JEOL Eclipse™ 400 MHz spectrometer or a Varian UnityPlus™ 400 MHz spectrometer, corresponding to a ¹³C resonance frequencyof 100.5 MHz. The data are acquired using 4000 transients per data filewith a 6 second pulse repetition delay. To achieve minimumsignal-to-noise for quantitative analysis, multiple data files are addedtogether. The spectral width is 25,000 Hz with a minimum file size of32K data points. The samples are analyzed at 130° C. in a 10 mm broadband probe. The comonomer incorporation is determined using Randall'striad method (Randall, J. C.; JMS-Rev. Macromol. Chem. Phys., C29,201-317 (1989), which is incorporated by reference herein in itsentirety).

Mechanical Properties—Tensile, Hysteresis, and Tear

Stress-strain behavior in uni-axial tension is measured using ASTM D1708 microtensile specimens. Samples are stretched with an Instron at500% min⁻¹ at 21° C. Tensile strength and elongation at break arereported from an average of 5 specimens.

100% and 300% hysteresis are determined from cyclic loading to 100% and300% strains using ASTM D 1708 microtensile specimens with an Instron™instrument. The sample is loaded and unloaded at 267% min⁻¹ for 3 cyclesat 21° C. Cyclic experiments at 300% and 80° C. are conducted using anenvironmental chamber. In the 80° C. experiment, the sample is allowedto equilibrate for 45 minutes at the test temperature before testing. Inthe 21° C., 300% strain cyclic experiment, the retractive stress at 150%strain from the first unloading cycle is recorded. Percent recovery forall experiments are calculated from the first unloading cycle using thestrain at which the load returned to the base line. The percent recoveryis defined as:

${\%\mspace{14mu}{Recovery}} = {\frac{ɛ_{f} - ɛ_{s}}{ɛ_{f}} \times 100}$where ε_(f) is the strain taken for cyclic loading and ε_(s) is thestrain where the load returns to the baseline during the 1^(st)unloading cycle.

Block Index

The ethylene/α-olefin interpolymers are characterized by an averageblock index, ABI, which is greater than zero and up to about 1.0 and amolecular weight distribution, M_(w)/M_(n), greater than about 1.3. Theaverage block index, ABI, is the weight average of the block index(“BI”) for each of the polymer fractions obtained in preparative TREF(i.e., fractionation of a polymer by Temperature Rising ElutionFractionation) from 20° C. and 110° C., with an increment of 5° C.(although other temperature increments, such as 1° C., 2° C., 10° C.,also may be used):ABI=Σ(w _(i) BI _(i))where BI_(i) is the block index for the ith fraction of theethylene/α-olefin interpolymer obtained in preparative TREF, and w_(i)is the weight percentage of the ith fraction. Similarly, the square rootof the second moment about the mean, hereinafter referred to as thesecond moment weight average block index, may be defined as follows:

${2^{nd}\mspace{11mu}{moment}\mspace{14mu}{weight}\mspace{14mu}{average}\mspace{14mu}{BI}} = \sqrt{\frac{\sum\left( {w_{i}\left( {{BI}_{i} - {ABI}} \right)}^{2} \right)}{\frac{\left( {N - 1} \right){\sum w_{i}}}{N}}}$where N is defined as the number of fractions with BI_(i) greater thanzero. BI is defined by one of the two following equations (both of whichgive the same BI value):

${BI} = {{\frac{{1/T_{X}} - {1/T_{XO}}}{{1/T_{A}} - {1/T_{AB}}}\mspace{20mu}{or}\mspace{20mu}{BI}} = {- \frac{{{Ln}\; P_{X}} - {{Ln}\; P_{XO}}}{{{Ln}\; P_{A}} - {{Ln}\; P_{AB}}}}}$where T_(X) is the ATREF (i.e., analytical TREF) elution temperature forthe ith fraction (preferably expressed in Kelvin), P_(X) is the ethylenemole fraction for the ith fraction, which may be measured by NMR or IRas described below. P_(AB) is the ethylene mole fraction of the wholeethylene/α-olefin interpolymer (before fractionation), which also may bemeasured by NMR or IR. T_(A) and P_(A) are the ATREF elution temperatureand the ethylene mole fraction for pure “hard segments” (which refer tothe crystalline segments of the interpolymer). As an approximation orfor polymers where the “hard segment” composition is unknown, the T_(A)and P_(A) values are set to those for high density polyethylenehomopolymer.

T_(AB) is the ATREF elution temperature for a random copolymer of thesame composition (having an ethylene mole fraction of P_(AB)) andmolecular weight as the olefin block copolymer. T_(AB) may be calculatedfrom the mole fraction of ethylene (measured by NMR) using the followingequation:Ln P _(AB) =α/T _(AB)+βwhere α and β are two constants which may be determined by a calibrationusing a number of well characterized preparative TREF fractions of abroad composition random copolymer and/or well characterized randomethylene copolymers with narrow composition. It should be noted that αand β may vary from instrument to instrument. Moreover, one would needto create an appropriate calibration curve with the polymer compositionof interest, using appropriate molecular weight ranges and comonomertype for the preparative TREF fractions and/or random copolymers used tocreate the calibration. There is a slight molecular weight effect. Ifthe calibration curve is obtained from similar molecular weight ranges,such effect would be essentially negligible. In some embodiments, randomethylene copolymers and/or preparative TREF fractions of randomcopolymers satisfy the following relationship:Ln P=−237.83/T _(ATREF)+0.639

The above calibration equation relates the mole fraction of ethylene, P,to the analytical TREF elution temperature, T_(ATREF), for narrowcomposition random copolymers and/or preparative TREF fractions of broadcomposition random copolymers. T_(XO) is the ATREF temperature for arandom copolymer of the same composition (i.e., the same comonomer typeand content) and the same molecular weight and having an ethylene molefraction of P_(X). T_(XO) may be calculated from LnPX=α/T_(XO)+β from ameasured P_(X) mole fraction. Conversely, P_(XO) is the ethylene molefraction for a random copolymer of the same composition (i.e., the samecomonomer type and content) and the same molecular weight and having anATREF temperature of T_(X), which may be calculated from LnP_(XO)=α/T_(X)+β using a measured value of T_(X).

Once the block index (BI) for each preparative TREF fraction isobtained, the weight average block index, ABI, for the whole polymer maybe calculated.

Melting Point and Crystallinity

Differential scanning calorimetry (DSC) is a common technique that canbe used to examine the melting and crystallization of semi-crystallinepolymers. General principles of DSC measurements and applications of DSCto studying semi-crystalline polymers are described in standard texts(e.g., E. A. Turi, ed., Thermal Characterization of Polymeric Materials,Academic Press, 1981). For example, DSC analysis may be determined usinga model Q1000 DSC from TA Instruments, Inc, which is calibrated usingindium and deionized water. After heating the sample rapidly to 230° C.and holding for 3 minutes, the cooling curve is obtained by cooling at10° C./min to −40° C. After holding at −40° C. for 3 minutes, the DSCmelting endotherm is recorded while heating at 10° C./min. The meltingpoint is determined using the standard TA DSC software.

These propylene-rich polymers can be made by a number of processes, suchas by single stage, steady state, polymerization conducted in awell-mixed continuous feed polymerization reactor. In addition tosolution polymerization, other polymerization procedures such as gasphase or slurry polymerization may be used. Other suitable processes forpreparing such polymers are described in U.S. Pat. No. 6,525,157,incorporated by reference in its entirety.

A typical isotactic polymerization process consists of a polymerizationin the presence of a catalyst including a bis(cyclopentadienyl) metalcompound and either (1) a non-coordinating compatible anion activator,or (2) an alumoxane activator. According to one embodiment, this processcomprises the steps of contacting ethylene and propylene with a catalystin a suitable polymerization diluent, the catalyst including, in oneembodiment, a chiral metallocene compound, e.g., a bis(cyclopentadienyl)metal compound as described in U.S. Pat. No. 5,198,401, and anactivator. U.S. Pat. No. 5,391,629 also describes catalysts useful toproduce the some copolymers suitable in dispersions described herein.Gas phase polymerization processes are described in U.S. Pat. Nos.4,543,399, 4,588,790, 5,028,670, for example. Methods of supportingmetallocene catalysts useful for making some copolymers used embodimentsof the invention are described in U.S. Pat. Nos. 4,808,561, 4,897,455,4,937,301, 4,937,217, 4,912,075, 5,008,228, 5,086,025, 5,147,949, and5,2388,92. Numerous examples of the biscyclopentadienyl metallocenesdescribed above for the invention are disclosed in U.S. Pat. Nos.5,324,800; 5,198,401; 5,278,119; 5,387,568; 5,120,867; 5,017,714;4,871,705; 4,542,199; 4,752,597; 5,132,262; 5,391,629; 5,243,001;5,278,264; 5,296,434; and 5,304,614. Descriptions of ionic catalysts forcoordination polymerization including metallocene cations activated bynon-coordinating anions appear in the early work in EP-A-0 277 003,EP-A-0 277 004, U.S. Pat. Nos. 5,198,401 and 5,278,119, and WO 92/00333.The use of ionizing ionic compounds not containing an active proton, butcapable of producing both the active metallocene cation and anon-coordinating anion, is also known. See, EP-A-0 426 637, EP-A-0 573403 and U.S. Pat. No. 5,387,568, EP-A-0 427 697 and EP-A-0 520 732.Ionic catalysts for addition polymerization can also be prepared byoxidation of the metal centers of transition metal compounds by anionicprecursors containing metallic oxidizing groups along with the aniongroups; see EP-A-0 495 375.

Some polymers can be prepared by a polymerization process comprising:reacting propylene and at least one comonomer selected from the groupconsisting of ethylene and at least one C₄ to C₂₀ alpha-olefin, underpolymerization conditions in the presence of a metallocene catalystcapable of incorporating the propylene sequences into isotactic orsyndiotactic orientations, in at least one reactor to produce a firstcopolymer having at least 65 mole percent propylene and whereinpreferably at least 40 percent of the propylene sequences are inisotactic or syndiotactic orientations; wherein the copolymer has a meltindex (MI) from about 7 dg/min to about 3000 dg/min. Some details of thepolymers are described in the following paragraphs.

Preferably, the propylene-rich polymer or polymer blend has a meltingpoint of 25 to 105° C.; from 60 to 120° C. in other embodiments, andfrom 80 to 100° C. in yet other embodiments. Also, the polymer orpolymer blend preferably includes ethylene (or an alpha olefin, e.g.,having from 4-20 carbon atoms) in the amount of up to 30 mole percent,preferably from 3 mole percent to 20 mole percent and more preferablyfrom 7 mole percent to 15 mole percent. In this context, the ethylene oralpha-olefin can be units forming part of a random semicrystallinecopolymer that includes both propylene units and ethylene units, e.g.,when a single copolymer is used (not a blend). Alternatively, a blendcan be used in which isotactic polypropylene is blended with apolyethylene, in which case the ethylene units in the polyethyleneshould be up to 30 mole percent of the overall polymer blend. Asdiscussed in greater detail below, it is contemplated that while thepresence of ethylene units may provide the desired melting point, thosesame ethylene units may cause crosslinking to such an extent that theMFR is decreased rather than increased, and for that reason, the amountof ethylene should be limited.

Preferably, a substantial portion of the propylene-rich polymer orpolymer blend melts within 40 to 120° C. One of ordinary skill in theart will appreciate that initiation of melt may begin at lowertemperatures. Also, the polymer or polymer blend preferably includesethylene (or an alpha-olefin, e.g., having from 4-20 carbon atoms) inthe amount of up to 30 mole percent, preferably from 3 mole percent to20 mole percent and more preferably from 7 mole percent to 15 molepercent. In this context, the ethylene or alpha-olefin can be unitsforming part of a random semicrystalline copolymer that includes bothpropylene units and ethylene units, e.g., when a single copolymer isused (not a blend). Alternatively, a blend can be used in whichisotactic polypropylene is blended with a polyethylene, in which casethe ethylene units in the polyethylene should be up to 30 mole percentof the overall polymer blend.

In other specific embodiments, the dispersions include a propylene-richpolymer or polymer blends wherein the composition preferably includes arandom copolymer produced by copolymerizing propylene and at least oneof ethylene or alpha-olefin having 20 or less carbon atoms, preferably 8or less carbon atoms, the random copolymer having a crystallinity atleast about 2 percent and no greater than about 65 percent derived fromstereoregular polypropylene sequences and a melting point of from about25° C. to about 105° C.

In still other specific embodiments, the propylene-rich copolymers arethe reaction product of a free radical initiator and a random copolymerproduced by copolymerizing propylene and at least one of ethylene oralpha-olefin having 8 or less carbon atoms, the random copolymer havinga crystallinity at least about 2 percent and no greater than about 65percent derived from stereoregular polypropylene sequences and a meltingpoint of from about 25° C. to about 105° C. For example, apropylene-ethylene copolymer having approximately 5 weight percentethylene may have a melting point of 115° C. or less in someembodiments; in other embodiments, a propylene-ethylene copolymer havingapproximately 5.4 weight percent ethylene may have a melting point of96° C. or less. Additional examples of propylene-ethylene copolymers arepresented in Table 2, which were made using catalysts as described inU.S. Pat. No. 6,960,635.

TABLE 2 Ethylene Content Melting Point Heat of Fusion (weight percent)(° C.) (J/g) 4.6 105.3 60.8 5.4 95.5 — 8.0 83.4 40.4 11.5 61.8 24.8 14.058.3  4.2

In yet another specific embodiment of this invention the dispersionincludes a random polymer with a melting point between about 40° C. and140° C. The viscosity as measured by melt flow rate at 230° C. should bebetween 2 and 5600, more preferably between 70 and 370, and mostpreferably between 300 and 1800 centipoise. Correspondingly, the meltindex, measured at 190° C., should be between 20 and 1500, morepreferably between 40 and 1000, and most preferably between 100 and 500dg/minute. Further, the tensile elongation of the polymer at roomtemperature should be in excess of 50 percent, more preferably in excessof 100 percent, and most preferably in excess of 300 percent.Preferably, the random copolymer is a low molecular weight copolymercontaining propylene units in an amount of 80 percent or above,preferably more than 90 percent, with the propylene units preferablybeing predominantly isotactic sequences (more than 80 percent of theunits being isotactic pentads), as measured by ¹³C NMR. The randomcopolymers can have long chain branching, providing greater flexibilityfor desired rheological properties.

Still other dispersions can include a polyolefin composition containinga physical blend, wherein an ethylene-propylene copolymer is blendedtogether with isotactic polypropylene. Those ethylene-propylenecopolymers are preferably derived by solution polymerization usingchiral metallocene catalysts. Those ethylene-propylene copolymerspreferably have crystallinity derived from isotactic propylenesequences. In those blend compositions, the composition of thecopolymers includes up to 30 weight percent and preferably up to 20weight percent ethylene. Those copolymers may be linear or branched.Those blends preferably contain substantial amounts of isotacticpolypropylene, at least about 5 to 10 weight percent. In a specificembodiment, the blend can include isotactic polypropylene in an amountup to about 50 weight percent, or alternatively up to about 80 weightpercent. The blend can also include other olefin-based polymers, such asreactor copolymers and impact copolymers. Desirably, the use of theblends described above provide for favorable melting temperatures due tothe presence of the isotactic polypropylene while providing a separatemolecular architecture for the copolymer, thus improving the rheology,elasticity and flexibility of the adhesive composition.

In still other embodiments, some dispersions include a thermoplasticresin selected from copolymers and interpolymers of ethylene and/orpropylene and other monomers selected from C₄ to C₁₀ olefins, preferablyalpha-olefins, more preferably from C₄ to C₈ alpha-olefins and mostpreferably selected from n-butene, n-hexene and n-octene. The ethyleneor propylene content of the thermoplastic resin ranges from about 2 to98 weight percent of the resin.

In some embodiments, a primarily ethylene-based polyolefin is selectedin which ethylene comprises from about 98 to 65 weight percent ofpolymer. In other embodiments, a primarily propylene-based polyolefinmay be selected, propylene comprising from about 98 to 65 weight percentof the Polymer. Selected comonomer(s) make up the remainder of thepolymer.

In some such embodiments, the ethylene polymer has the followingcharacteristics and properties: 1) crystallinity as determined by theobservance of at least one endotherm when subjected to standarddifferential scanning calorimetry (DSC) evaluation; 2) a melt index ofbetween about 30 and about 0.1 g/10 min, preferably of between 25 and0.25 g/10 min, more preferably of between 22 and 0.5 g/10 min, and mostpreferably of between 18 and 0.75 g/10 min; and 3) a density asdetermined according to ASTM D-792 of between about 0.845 and about0.925 g/cc, preferably between 0.85 and 0.91 g/cc, and more preferablybetween 0.855 and 0.905 g/cc, and most preferably between 0.86 and 0.90g/cc.

One class of resins particularly suited to use in embodiments of theinvention are copolymers of ethylene and 1-octene or 1-butene, whereethylene comprises from about 90 to about 50, more preferably 85 to 55,and 1-octene or 1-butene from about 10 to about 50, more preferablyabout 15 to 45 percent by weight of the copolymer, and that have a MeltIndex between about 0.25 and about 30, more preferably between 0.5 and20 g/10 min. Alternatively, instead of a single polymer, a blend ofpolymers may be employed that has the physical characteristics describedabove. For example, it may be desirable to blend a first polymer withrelatively high MI that is outside the range described above, withanother of relatively low MI, so that the combined MI and the averageddensity of the blend fall within the ranges noted above.

In addition to the thermoplastic resin, dispersions described hereininclude a dispersing agent. Any dispersing agent may be used inembodiments of the invention. As used herein the term “dispersing agent”means an agent that aids in the formation and/or the stabilization of adispersion. Some dispersing agents can also be used to form emulsionsand are described in detail by Paul Becher (Emulsions: Theory andPractice, 3rd edition, Oxford University Press, New York, 2001),incorporated herein by reference in its entirety. Dispersing agentsgenerally fall into three classes 1) surface-active materials, 2)naturally occurring materials, 3) finely divided solids. Surface-activeagents, also called surfactants, are materials that reduce theinterfacial tension between two immiscible liquid phases. They areclassified according to the hydrophilic group in the molecule: anionic,cationic, nonionic, or ampholytic (amphoteric). Examples of commerciallyavailable dispersing agents are found in McCutcheon (McCutcheon'sEmulsifiers and Detergents, Glen Rock, N.J., issued annually). Examplesof naturally occurring materials include phospholipids, sterols,lanolin, water-soluble gums, alginates, carageenin, and cellulosederivatives. Examples of finely divided solids include basic salts ofthe metals, carbon black, powdered silica, and various clays(principally bentonite).

In some embodiments, a carboxylic acid or carboxylic acid salt is usedas the dispersing agent. Typical salts include alkaline earth metalsalts or alkaline earth metal salts of a fatty acid. Other salts includeammonium or alkyl ammonium salts of the carboxylic acid. In someembodiments, the carboxylic acid or it's salt with 12 to fewer than 25carbon atoms. Where the dispersing agent is a salt, the number ofcarbons refers to the carbon atoms associated with the carboxylic acidfragment. In other embodiments, the salt is formed with a fatty acidfragment that has at from 15 to 25 carbon atoms. Particular embodimentsuse an alkali metal salt of erucic acid. Erucic acid is a carboxylicacid with 22 carbon atoms. Some embodiments use erucic acid in the formof rapeseed oil, a natural oil that contains approximately 40 to about50 percent erucic acid with the remainder consisting of primarily chainshaving 18 carbon atoms. An alkali metal salt of erucic acid is alsouseful in some embodiments.

Some embodiments of the present invention use a fatty acid or its saltthat is derived from an ester of a fatty acid. The alcohol residueconstituting such ester may preferably contain 2 to 30 carbon atoms, andmost preferably 6 to 20 carbon atoms. Such residue may be either astraight or a branched residue, and may also be a mixture of two or moreresidues each containing different number of carbon atoms. Exemplarysuch alcohol residues include residues of higher alcohols containing 10to 20 carbon atoms such as cetyl alcohol, stearyl alcohol, and oleylalcohol. Some embodiments use an ester wax of erucic acid.

In particular embodiments the salt of a fatty acid containing fewer than25 carbon atoms is produced by neutralizing a fatty acid containingfewer than 25 carbon atoms or by saponification of an ester of a fattyacid containing fewer than 25 carbon atoms.

In other embodiments, the dispersing agent can be an ethylene acrylicacid copolymer. Still other embodiments use alkyl ether carboxylates asthe dispersing agent. In some embodiments, petroleum sulfonates areuseful. In other embodiments, the dispersing agent is a sulfonated orpolyoxyethylenated alcohol. In still other embodiments, sulfated orphosphated polyoxyethylenated alcohols are suitable. Polymeric ethyleneoxide/propylene oxide/ethylene oxide dispersing agents, known aspoloxamers are used as the dispersing agent in some embodiments. Primaryand secondary alcohol ethoxylates are also suitable in some dispersions.Alkyl glycosides and alkyl glycerides are used in some dispersions. Ofcourse, combinations of these dispersing agents are also suitable.

Embodiments of the aqueous dispersions described herein contain water inaddition to the components as described above. Deionized water istypically preferred. In some embodiments, water with excess hardness canundesirably affect the formation of a suitable dispersion. Particularlywater containing high levels of alkaline earth ions, such as Ca²⁺,should be avoided. The term “dispersion” as used herein refers to afinely divided solid or liquid in a continuous liquid medium. An aqueousdispersion is a dispersion in which the continuous liquid medium iswater. The term “dispersion” as used herein in connection with thecompositions of the invention is intended to include within its scopeboth emulsions of essentially liquid materials, prepared employing thethermoplastic resin and the dispersing agent, and dispersions of solidparticles. Such solid dispersions can be obtained, for example, bypreparing an emulsion as previously described, and then causing theemulsion particle to solidify by various means. Thus, when thecomponents are combined, some embodiments provide an aqueous dispersionwherein content of the dispersing agent is present in the range of from0.5 to 30 parts by weight, and content of (C) water is in the range of 1to 35 parts by weight per 100 parts by weight of the thermoplasticpolymer; and total content of (A) and (B) is in the range of from 65 to99 percent by weight. In particular embodiments, the dispersing agentranges from 2 to 20 parts by weight based on 100 parts by weight of thepolymer. In some embodiments, the amount of dispersing agent is lessthan about 4 percent by wt., based on the weight of the thermoplasticpolymer. In some embodiments, the dispersing agent comprises from about0.5 percent by weight to about 3 percent by weight, based on the amountof the thermoplastic polymer used. In other embodiments, about 1.0 toabout 3.0 weight percent of the dispersing agent is used. Embodimentshaving less than about 4 weight percent dispersing agent are preferredwhere the dispersing agent is a carboxylic acid.

Embodiments of the aqueous dispersion disclosed herein may also includea solvent, such as a light hydrocarbon, for example. In someembodiments, solvents added to the dispersion may improve filmformation. In other embodiments, solvents may improve the wetting of thedispersion on a substrate, such as plastic substrates. Solvent usefulherein may include C₄ to C₁₂ hydrocarbons, including linear, branched,cyclic, and aromatic hydrocarbons.

One feature of some embodiments of the invention is that the dispersionshave a small particle size. Typically the average particle size is lessthan about 5 μm. Some preferred dispersions have an average particlesize of less than about 1.5 μm. In some embodiments, the upper limit onthe average particle size is about 4.5 μm, 4.0 μm, 3.75 μm, 3.5 μm, 3.25μm, 3.0 μm, 2.5 μm, 2.0 μm, 1.5 μm, 1.0 μm, 0.5 μm, or 0.1 μm. Someembodiments have a lower limit on the average particle size of about0.05, 0.07 μm, 0.1 μm, 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, or 2.5 μm. Thus,some particular embodiments have, for example, an average particle sizeof from about 0.05 μm to about 1.5 μm. While in other embodiments, theparticles in the dispersion have an average particle size of from about0.5 μm to about 1.5 μm. For particles that are not spherical thediameter of the particle is the average of the long and short axes ofthe particle. Particle sizes can be measured on a Coulter LS230light-scattering particle size analyzer or other suitable device.

Another parameter that characterizes particles in the dispersions is theparticle size distribution, defined herein as the volume averageparticle diameter (Dv) divided by number average particle diameter (Dn).Some embodiments are characterized by a particle size distribution ofless than or equal to about 2.0. In other embodiments, the dispersionshave a particle size distribution of less than or equal to about lessthan 1.9, 1.7, or 1.5.

In yet another particular embodiment the aqueous dispersion has aconcentration of the solid content including (A) thermoplastic resin isin the range of from 10 to 70 percent. Another measure of solids contentis by volume. In some embodiments, the dispersion has a percent solid ofless than about 74 percent by volume. Other dispersions have a solidcontent of from about 5 percent to about 74 percent by volume. In someembodiments, the dispersions have a percent solid of less than about 70percent by volume, less than about 65 percent by volume, or ranging fromabout 5 percent to about 50 percent by volume.

One feature of some of the dispersions described herein is the pH, whichcan affect the uses for which dispersions are suitable. Typically, thedispersions have a pH of less than 12. Preferably, the pH ranges fromabout 5 to about 11.5, preferably from about 7 to about 11. morepreferably from about 9 to about 11. However, dispersions having a lowerlimit of the pH of about 5, about 6, about 7, about 8, about 9, about10, or about 11 are contemplated. Dispersions having an upper limit onthe pH of about 6, about 7, about 8, about 9, about 10, about 11, orabout 12 are contemplated.

While any method may be used, one convenient way to prepare thedispersions described herein is by melt-kneading. Any melt kneadingmeans known in the art may be used. In some embodiments a kneader, aBANBURY mixer, single-screw extruder, or a multi-screw extruder is used.The melt kneading may be conducted under the conditions which aretypically used for melt kneading the thermoplastic resin (A). A processfor producing the dispersions in accordance with the present inventionis not particularly limited. One preferred process, for example, is aprocess comprises melt-kneading the above-mentioned components accordingto U.S. Pat. No. 5,756,659 and U.S. Pat. No. 6,455,636. A preferredmelt-kneading machine is, for example, a multi screw extruder having twoor more screws, to which a kneading block can be added at any positionof the screws. If desired, it is allowable that the extruder is providedwith a first material-supplying inlet and a second material-supplyinginlet, and further third and forth material-supplying inlets in thisorder from the upper stream to the down stream along the flow directionof a material to be kneaded. Further, if desired, a vacuum vent may beadded at an optional position of the extruder. In some embodiments, thedispersion is first diluted to contain about 1 to about 3 percent byweight of water and then subsequently further diluted to comprisegreater than 25 percent by weight of water. In some embodiments, thefurther dilution provides a dispersion with at least about 30 percent byweight of water. The aqueous dispersion obtained by the melt kneadingmay be further supplemented with an aqueous dispersion of anethylene-vinyl compound copolymer, or a dispersing agent.

FIG. 1 schematically illustrates such an extrusion apparatus embodimentsof the invention. An extruder, in certain embodiments a twin screwextruder, 20 is coupled to a back pressure regulator, melt pump, or gearpump, 30. Embodiments also provide a base reservoir 40 and an initialwater reservoir 50, each of which includes a pump (not shown). Desiredamounts of base and initial water are provided from the base reservoir40 and the initial water reservoir 50, respectively. Any suitable pumpmay be used, but in some embodiments a pump that provides a flow ofabout 150 cc/min at a pressure of 240 bar may be used to provide thebase and the initial water to the extruder 20. In other embodiments, aliquid injection pump provides a flow of 300 cc/min at 200 bar or 600cc/min at 133 bar. In some embodiments the base and initial water arepreheated in a preheater.

Resin, in the form of pellets, powder, or flakes, is fed from the feeder80 to an inlet 90 of the extruder 20 where the resin is melted orcompounded. In some embodiments, the dispersing agent is added to theresin through an opening along with the resin and in other embodiments,the dispersing agent is provided separately to the twin screw extruder20. The resin melt is then delivered from the mix and convey zone to anemulsification zone of the extruder where the initial amount of waterand base from the reservoirs 40 and 50 is added through inlet 55. Insome embodiments, dispersing agent may be added additionally orexclusively to the water stream. In some embodiments, the emulsifiedmixture is further diluted with additional water via inlet 95 fromreservoir 60 in a dilution and cooling zone of the extruder 20.Typically, the dispersion is diluted to at least 30 weight percent waterin the cooling zone. In addition, the diluted mixture may be diluted anynumber of times until the desired dilution level is achieved. In someembodiments, water is not added into the twin screw extruder 20 butrather to a stream containing the resin melt after the melt has exitedfrom the extruder. In this manner, steam pressure build-up in theextruder 20 is eliminated.

In some embodiments a basic substance or aqueous solution, dispersion orslurry thereof is added to the dispersion at any point of the process,preferably to the extruder. Typically the basic substance is added as anaqueous solution. But in some embodiments, it is added in otherconvenient forms, such as pellets or granules. In some embodiments, thebasic substance and water are added through separate inlets of theextruder. Examples of the basic substance which may be used for theneutralization or the saponification in the melt kneading processinclude alkaline metals and alkaline earth metals such as sodium,potassium, calcium, strontium, barium; inorganic amines such ashydroxylamine or hydrazine; organic amines such as methylamine,ethylamine, ethanolamine, cyclohexylamine, tetramethylammoniumhydroxide; oxide, hydroxide, and hydride of alkaline metals and alkalineearth metals such as sodium oxide, sodium peroxide, potassium oxide,potassium peroxide, calcium oxide, strontium oxide, barium oxide, sodiumhydroxide, potassium hydroxide, calcium hydroxide, strontium hydride,barium hydroxide, sodium hydride, potassium hydride, calcium hydride;and weak acid salts of alkaline metals and alkaline earth metals such assodium carbonate, potassium carbonate, sodium hydrogencarbonate,potassium hydrogencarbonate, calcium hydrogencarbonate, sodium acetate,potassium acetate, calcium acetate; or ammonium hydroxide. In particularembodiments, the basic substance is a hydroxide of an alkaline metal ora hydroxide of an alkali metal. In some embodiments, the basic substanceis selected from potassium hydroxide, sodium hydroxide and combinationsthereof.

The aqueous dispersion may be coated onto a substrate by variousprocedures, and for example, by spray coating, curtain flow coating,coating with a roll coater or a gravure coater, brush coating, dipping.The coating is preferably dried by heating the coated substrate to 50 to150° C. for 1 to 300 seconds although the drying may be accomplished byany suitable means.

The substrate for coatings may comprise a film of a thermoplastic resinsuch as polypropylene, polyethylene terephthalate, polyethylene, otherpolyolefins, oriented polyolefins, such as biaxially orientedpolypropylene, polycarbonate, polyimide, polyamide, polyphenylenesulfide, polysulfone, aromatic polyester, polyether ether ketone,polyether sulfone, and polyether imide. The preferred substrate is afilm comprising polyethylene terephthalate, polyethylene, polyamide,and/or polycarbonate, and the most preferred substrate is a filmcomprising polypropylene, and in particular, biaxially orientedpolypropylene. Typically the films have a thickness in the range of from0.5 to 50 microns, although some have a thickness of from 1 to 30microns.

Some embodiments of the dispersions described herein are capable offorming a coating which exhibits excellent water resistance, oilresistance, or chemical resistance. Some embodiments exhibit adhesion tonon-polar materials, and therefore, when the aqueous dispersion of thepresent invention is coated and dried on the surface of a substrate suchas paper, fiber, wood, metal, or plastic molded article, the resultingresin coating will provide the substrate with water resistance, oilresistance, chemical resistance, corrosion resistance and heatsealability. Coatings obtained from some dispersions described hereinexhibit excellent moisture resistance, water repellency, thermaladhesion to paper, especially for water and/or grease barrier and inkadhesion coatings layers, metal, glass, wood, fiber (natural fiber andsynthetic fiber), and non-woven fabric, thermal transfer properties,abrasion resistance, impact resistance, weatherability, solventresistance, flexibility, and adaptability to high-frequency fabricating.Some dispersions are particularly suited for the formation of textilecoatings including fabric impregnation. Some dispersions are alsosuitable for use as carpet backing layers. Coatings for architecturalworks are also contemplated as well as coatings for controlled releasecoatings on fertilizer pellets or as coatings to control surfaceproperties such as coefficient of friction. Additionally somedispersions can be used to prepare stable froths and foams, as describedin “PCT Publication No. WO2005021622 and U.S. Patent ApplicationPublication No. 20060211781.

Some aqueous dispersions described herein are used as a binder in acoating composition for a coated wall paper; a fiber coating agent (forimproving the strength, moisture adsorption, or water repellency of thefiber); a net for construction, a sizing agent for nylon, polyester orglass fibers; a sizing agent/thermal adhesive of a paper or a non-wovenfabric; and an agent for imparting heat sealability with a paper or afilm; a thermal adhesive of a sterilized paper; a binder of an ink or acoating composition; a surface coating agent for a paper or a filmadapted for use with an ink jet printer; an agent for improving chippingresistance of an automotive coating composition; and the like.

In some embodiments, the aqueous dispersions have additional componentsin an amount that does not adversely affect the object of the presentinvention. Exemplary such additional components include water-solubleamino resins such as water-soluble melamine resin and water-solublebenzoguanamine resin and water-soluble epoxy resins for improvingcoating performance; organic thickeners such as polyvinyl alcohol,polyvinyl pyrrolidone, polyvinyl methylether, polyethylene oxide,polyacrylamide, polyacrylic acid, carboxy methyl cellulose, methylcellulose, and hydroxyethyl cellulose and inorganic thickeners such assilicon dioxide, active clay, and bentonite for improving the stabilityand adjusting the viscosity of the dispersion; dispersing agents such asnonionic dispersing agents and anionic dispersing agents andwater-soluble polyvalent metal salts for improving the stability of thedispersion; other additives such as anti-rust agent, anti-mold agent, UVabsorber, thermal stabilizer, foaming agent, antifoaming agent, and thelike; pigments such as titanium white, red iron oxide, phthalocyanine,carbon black, permanent yellow; and fillers such as calcium carbonate,magnesium carbonate, barium carbonate, talk, aluminum hydroxide, calciumsulfate, kaolin, mica, asbestos, mica, and calcium silicate.

As discussed above, aqueous dispersions made in accordance withembodiments described herein may be particularly useful in creatingcoatings for various substrates. In some embodiments, substrates mayinclude, but are not limited to, polypropylene, polyethyleneterephthalate, polyethylene, other polyolefins, oriented polyolefins,such as biaxially oriented polypropylene (BOPP), polycarbonate,polyimide, polyamide, polyphenylene sulfide, polysulfone, aromaticpolyester, polyether ether ketone, polyether sulfone, and polyetherimide. In other embodiments, substrates may include glass, paper, metal,glass, wood, fiber (natural fiber and synthetic fiber), and non-wovenfabrics. In selected embodiments, metals may include aluminum, copper,brass, and steel. After drying, the resultant film may be useful in anumber of applications, including water and/or grease barriers, thermaltransfer properties, abrasion resistance, impact resistance,weatherability, solvent resistance, flexibility, and adaptability tohigh-frequency fabricating.

FIG. 2 is a flowchart describing one embodiment of the presentinvention. As shown in FIG. 2, the first step in the process is toproduce an aqueous polymer dispersion (step 200). The next step (step202) is to coat a substrate with the dispersion. The coated substrate isthen dried to form the final product (step 204). Each of the steps willbe explained in more detail below.

Forming the Dispersion (Step 200)

This step is discussed in detail in the paragraphs above. However, somediscussion is provided below for the sake of clarity. In forming thedispersion, it is important to note that the resin(s) that provide thebasis for the dispersion is a significant element and controls ormodifies at least the following characteristics:

-   -   Heat seal behavior—heat seal initiation temperature, seal        strength, and hot tack;    -   Adhesion to base film substrate; and    -   Film formation characteristics—during the drying of the        dispersion, the particles preferably would coalesce to form a        coherent, transparent layer.

Examples of polymers that may be used in embodiments disclosed hereininclude AFFINITY™ EG 8200 co-polymer (0.870 g/cc, 5 MI) and/or DE4300.02 a propylene based copolymer (12% ethylene, 25 MFR), both ofwhich are available from The Dow Chemical Company, Midland, Mich. Bothpolymers provide a low heat seal initiation temperature, good adhesionto substrates, and can form a film when dried.

In other embodiments, a copolymer of propylene, ethylene and,optionally, one or more unsaturated comonomers, e.g., C₄₋₂₀ α-olefins,C₄₋₂₀ dienes, vinyl aromatic compounds (e.g., styrene), etc., may beused. These copolymers are characterized as comprising at least about 60weight percent of units derived from propylene, about 0.1-35 weightpercent of units derived from ethylene, and 0 to about 35 weight percentof units derived from one or more unsaturated comonomers, with theproviso that the combined weight percent of units derived from ethyleneand the unsaturated comonomer does not exceed about 40 weight percent.These copolymers are also characterized as having at least one of thefollowing properties: (i) ¹³C NMR peaks corresponding to a regio-errorat about 14.6 and about 15.7 ppm, the peaks of about equal intensity,(ii) a skewness index, S_(ix), greater than about −1.20, (iii) a DSCcurve with a T_(me) that remains essentially the same and a T_(max) thatdecreases as the amount of comonomer, i.e., the units derived fromethylene and/or the unsaturated comonomer(s), in the copolymer isincreased.

In other embodiments, a copolymer of propylene and one or moreunsaturated comonomers may be used. These copolymers are characterizedin having at least about 60 wt % of the units derived from propylene,and between about 0.1 and 40 wt % the units derived from the unsaturatedcomonomer. These copolymers are also characterized as having at leastone of the following properties: (i) ¹³C NMR peaks corresponding to aregio-error at about 14.6 and about 15.7 ppm, the peaks of about equalintensity, (ii) a skewness index, S_(ix), greater than about −1.20,(iii) a DSC curve with a T_(me) that remains essentially the same and aT_(max) that decreases as the amount of comonomer, i.e., the unitsderived from the unsaturated comonomer(s), in the copolymer isincreased.

In other embodiments, a blend of two or more copolymers, in which atleast one copolymer is at least one of the propylene/ethylene andpropylene/unsaturated comonomer copolymers described above (individuallyand collectively “P/E* copolymer”), may be used. The amount of eachcomponent in the blend can vary to convenience. The blend may containany weight percent, based on the total weight of the blend, of eithercomponent, and the blend may be either homo- or heterophasic. If thelatter, the copolymer of the first or second embodiment of thisinvention can be either the continuous or discontinuous (i.e.,dispersed) phase.

In other embodiments, the invention relates to a blend of (a) at leastone propylene homopolymer, and (b) at least one other polymer, e.g. anEP or EPDM rubber. The propylene homopolymer is characterized as having¹³C NMR peaks corresponding to a regio-error at about 14.6 and about15.7 ppm, the peaks of about equal intensity. Preferably, the propylenehomopolymer is characterized as having substantially isotactic propylenesequences, i.e., the sequences have an isotactic triad (mm) measured by¹³C NMR of greater than about 0.85.

The at least one other polymer of (b) may be a polyolefin such as one ormore of a polyethylene, ethylene/α-olefin, butylene/α-olefin,ethylene/styrene and the like. The blend may contain any weight percent,based on the total weight of the blend, of either component, and theblend may be either homo- or heterophasic. If the latter, the propylenehomopolymer can be either the continuous or dispersed phase.

Methods for forming these types of polymers are disclosed in U.S. PatentApplication Publication No. 20030204017, which is expressly incorporatedby reference in its entirety.

Further, as discussed in the dispersion section above, a surfactant (ormixture of surfactants) may be used to stabilize the dispersion. Byjudiciously selecting the surfactant or surfactants, it is possible tocontrol or modify at least some of the following characteristics:

-   -   Dispersion particle size;    -   Film formation characteristics;    -   Shear and shelf stability—the ability of the dispersion to        withstand high shear (shear stability) and extended time (shelf        stability) without a significant change in dispersion properties        (e.g., particle size);    -   Wettability—the ability to flow onto a substrate without        “drawing back” or “beading” on the substrate; and    -   Adhesion to a substrate.

As noted above, the surfactant may be a single surfactant or a blend ofseveral surfactants. The surfactant selected should be able to initiallydisperse the desired polymer or polymer solution. Selected surfactantsthat are effective for this include long chain fatty acids (C₁₈ throughC₃₂) neutralized via a base (typically NaOH, KOH, and NH₄OH). Oneparticular example of this type is oleic acid neutralized via KOH. Othersurfactants include ethylene-acrylic acid copolymers neutralized via abase. One example is PRIMACOR™ 59801 copolymer (20 wt % acrylic acid,300 MI, available from The Dow Chemical Company, Midland, Mich.)neutralized via KOH. Another group of useful surfactants includessulfonic acid salts. One example is RHODOCAL™ DS-10 surfactant (sodiumdodecylbenzene sulfonate, available from Rhodia, Inc. Cranbury, N.J.).

In addition to the surfactant used to initially disperse the polymer,additional surfactants may be added to improve characteristics such aswettability and shear stability. Sulfonic acid salts have proven to beeffective in this capacity.

One specific example of a surfactant package for the polyolefindispersion includes long chain fatty acids from C₁₂ to C₆₀ in an amountfrom 0 to 10 percent by weight based on polymer, ethylene-acrylic acid(EAA) in an amount from 0 to 50 percent by weight based on polymer, andsulfonic acid salts in an amount from 0 to 10 percent by weight based onpolymer, wherein the total surfactant loading is less than about 50percent by weight based on polymer. In other embodiments, the totalsurfactant loading may be less than about 10 percent by weight based onpolymer. In other embodiments, the total surfactant loading may be lessthan about 5 percent based on polymer. In specific embodiments,neutralization of the long chain fatty acids and the EAA is by additionof a base in an amount ranging from 25 to 200 percent on a molar basis.

In another embodiment, a surfactant package for the polyolefindispersion includes long chain fatty acids from C₁₂ to C₄₀ in an amountfrom 0 to 5 percent by weight based on polymer, ethylene-acrylic acid inan amount from 0 to 30 percent by weight based on polymer, and sulfonicacid salts in an amount from 0 to 5 percent by weight based on polymer,wherein the total surfactant loading is 1.0 percent by weight based onpolymer. In specific embodiments, neutralization of the long chain fattyacids and the EAA is by addition of a base from 50 to 150 percent on amolar basis.

In another embodiment, a surfactant package for the polyolefindispersion includes long chain fatty acids from C₁₈ to C₃₀ in an amountfrom 2 to 4 percent by weight based on polymer, and sulfonic acid saltsin an amount from 1 to 3 percent by weight based on polymer. In selectedembodiments, neutralization of the long chain fatty acids and the EAA isby addition of a base from 75 to 125 percent on a molar basis.

Another feature of dispersions in accordance with the invention that maybe controlled in order to provide useful coatings on substrates includescontrolling dispersion particle size. In selected embodiments, theaverage particle size (based on volume fraction) of the dispersion maybe less than 1 micron to achieve a transparent film at the low coatingthicknesses desired (1 to 2 micron dry coating thickness).

However, other particle sizes may be useful depending on the particularapplication selected. In some embodiments, the particle size of thedispersion may be <5 micron. In selected embodiments, the particle sizeof a dispersion may be <2 micron, and, in certain embodiments, theparticle size of a dispersion may be <1 micron.

Another aspect of a dispersion in accordance with the invention that maybe controlled is the solids content. A proper range of solids content ofa dispersion may prevent separation of the dispersed polymer particlesfrom the water and/or reduce the cost of transportation as less wateraccompanies the polymer. In selected embodiments, the solids content ofthe dispersion may be greater than 50 percent solids by weight. In someembodiments, the solids content of the dispersion is from 10 to 70percent solids by weight. In other embodiments, the solids content ofthe dispersion is from 20 to 60 percent solids by weight, and in otherembodiments, the solids content of the dispersion is from 40 to 55percent solids by weight.

Another aspect of dispersions in accordance with the invention that maybe controlled is the shear stability. The process of coating adispersion onto a film substrate at low thickness often requiresexposure of the dispersion to very high shear rates. In preferredembodiments, the dispersion is able to withstand this exposure withoutappreciable coagulation. In certain embodiments, it is desirable to haveless than 0.5 g of polymer coagulate based on a 100 g dispersion sampleexposed to the high shear.

Also, the overall pH of a dispersion may be significant in controllingthe wettability and adhesion of the dispersion onto the desired filmsubstrate. For low surface energy substrates such as biaxially orientedpolypropylene (BOPP), the pH of the dispersion is preferably less than11. In some embodiments, the pH of the dispersion is from 7.5 to 13. Inother embodiments, the pH of the dispersion is from 8 to 12, and inother embodiments, the pH of the dispersion is from 8 to 11.

Coating Application Conditions (Step 202)

After the dispersion has been produced, it is coated on to a substrate.With respect to the coating thickness, the thickness of the appliedcoating is important in controlling the hot tack and seal strength ofthe finished film. A coating thickness of 1 to 2 microns is typicallyneeded to generate a seal strength >200 g/in., which is a suitablestrength for a packaging application. Preferred thickness for the driedcoating is from 0.5 to 75 microns. In certain embodiments, a coatingthickness for the dried coating is from 0.5 to 25 microns. In otherembodiments, a coating thickness for the dried coating is from 0.75 to 5or from 0.75 to 2, microns.

Typical resins that may be used include the following resins alone andin blends: ethylene homopolymers such as LDPE, ethylene-vinyl compoundssuch as ethylene-vinyl acetate (EVA) and ethylene-methyl acrylate (EMA),ethylene-alpha olefin copolymers such as ethylene-butene,ethylene-hexene, and ethylene-octene copolymers, propylene homopolymers,and propylene copolymers and interpolymers such as propylene-ethylenecopolymers and propylene-ethylene-butene interpolymers.

More preferred polymers as coatings on BOPP and other polyolefinsubstrates include ethylene-octene copolymers having a density between0.85 and 0.90 g/cc and melt index (ASTM D-1238190° C. with 2.16 kgweight) from 0.1 to 100 g/10 min. Propylene-ethylene copolymers havingan ethylene content between 5 and 20% by weight and a melt flow rate(ASTM D-1238 230° C. with 2.16 kg weight) from 0.5 to 300 g/10 min. Morepreferably polymers as coatings on BOPP and other polyolefin substratesinclude ethylene-octene copolymers having a density between 0.86 and0.88 g/cc and melt index (ASTM D-1238190° C. with 2.16 kg weight) from0.8 to 35 g/10 min. In other embodiments, propylene-ethylene copolymershaving an ethylene content between 9 and 15% by weight and a melt flowrate (ASTM D-1238 230° C. with 2.16 kg weight) from 1 to 30 g/10 min areused.

Embodiments of the present invention are particularly suited for usewith oriented substrates. “Solid state orientation” herein refers to theorientation process carried out at a temperature higher than the highestTg (glass transition temperature) of resins making up the majority ofthe structure and lower than the highest melting point, of at least someof the film resins, that is at a temperature at which at least some ofthe resins making up the structure are not in the molten state. Solidstate orientation may be contrasted to “melt state orientation” that isincluding hot blown films, in which stretching takes place immediatelyupon emergence of the molten polymer film from the extrusion die.

“Solid state oriented” herein refers to films obtained by eitherco-extrusion or extrusion coating of the resins of the different layersto obtain a primary thick sheet or tube (primary tape) that is quicklycooled to a solid state to stop or slow crystallization of the polymers,thereby providing a solid primary film sheet, and then reheating thesolid primary film sheet to the so-called orientation temperature, andthereafter biaxially stretching the reheated film sheet at theorientation process (for example a trapped bubble method) or using asimultaneous or sequential tenter frame process, and finally rapidlycooling the stretched film to provide a heat shrinkable film. In thetrapped bubble solid state orientation process the primary tape isstretched in the transverse direction (TD) by inflation with airpressure to produce a bubble, as well as in the longitudinal direction(LD) by the differential speed between the two sets of nip rolls thatcontain the bubble. In the tenter frame process the sheet or primarytape is stretched in the longitudinal direction by accelerating thesheet forward, while simultaneously or sequentially stretching in thetransverse direction by guiding the heat softened sheet through adiverging geometry frame.

When referring to the average volume diameter of a thermoplastic resinin a dispersion, or a dispersion having an average volume diameterparticle size, one of ordinary skill in the art will recognize thatother materials such as filler may also be present in the dispersedparticles, and would be included in the diameter size. When measuringthe average volume diameter all the dispersed solids are included.

Substrates such as film and film structures particularly benefit fromthe novel coating methods and coating compositions described herein andthose substrates may be made using conventional hot blown filmfabrication techniques or other biaxial orientation processes such astenter frames or double bubble processes. Conventional hot blown filmprocesses are described, for example, in The Encyclopedia of ChemicalTechnology, Kirk-Othmer, Third Edition, John Wiley & amp; Sons, NewYork, 1981, Vol. 16, pp. 416-417 and Vol. 18, pp. 191-192. Biaxialorientation film manufacturing process such as described in a “doublebubble” process as in U.S. Pat. No. 3,456,044 (Pahlke), and theprocesses described in U.S. Pat. No. 4,352,849 (Mueller), U.S. Pat. No.4,597,920 (Golike), U.S. Pat. No. 4,820,557 (Warren), U.S. Pat. No.4,837,084 (Warren), U.S. Pat. No. 4,865,902 (Golike et al.), U.S. Pat.No. 4,927,708 (Herran et al.), U.S. Pat. No. 4,952,451 (Mueller), U.S.Pat. No. 4,963,419 (Lustig et al.), and U.S. Pat. No. 5,059,481 (Lustiget al.), may also be used to make substrates for coating by the novelcoating methods and coating compositions described herein. The substratefilm structures may also be made as described in a tenter-frametechnique, such as that used for oriented polypropylene.

Other multi-layer film manufacturing techniques for food packagingapplications are described in Packaging Foods With Plastics, by WilmerA. Jenkins and James P. Harrington (1991), pp. 19-27, and in“Coextrusion Basics” by Thomas I. Butler, Film Extrusion Manual Process,Materials, Properties pp. 31-80 (published by TAPPI Press' (1992)).

The substrate films may be monolayer or multilayer films. The substratefilm to be coated may also be coextruded with other layer(s) or the filmmay be laminated onto another layer (s) in a secondary operation to formthe substrate to be coated, such as that described in Packaging FoodsWith Plastics, by Wilmer A. Jenkins and James P. Harrington (1991) orthat described in “Coextrusion For Barrier Packaging” by W. J. Schrenkand C. R. Finch, Society of Plastics Engineers RETEC Proceedings, Jun.15-17 (1981), pp. 211-229. If a monolayer substrate film is produced viatubular film (that is, blown film techniques) or flat die (that is, castfilm) as described by K. R. Osborn and W. A. Jenkins in “Plastic Films,Technology and Packaging Applications” (Technomic Publishing Co., Inc.(1992)), then the film must go through an additional post-extrusion stepof adhesive or extrusion lamination to other packaging material layersto form a multilayer structure to be used as the substrate. If thesubstrate film is a co-extrusion of two or more layers (also describedby Osborn and Jenkins), the film may still be laminated to additionallayers of packaging materials, depending on the other physicalrequirements of the final film.

“Laminations vs. Coextrusion” by D. Dumbleton (Converting Magazine(September 1992)), also discusses lamination versus co-extrusion.Monolayer and coextruded films may also go through other post extrusiontechniques, such as a biaxial orientation process.

Extrusion coating is yet another technique for producing multilayer filmstructures as substrates to be coated using the novel coating methodsand coating compositions described herein. The novel coatingcompositions comprise at least one layer of the coated film structure.Similar to cast film, extrusion coating is a flat die technique.

The films and film layers of this invention are useful in vertical orhorizontal-form-fill-seal (HFFS or VFFS) applications. Relevant patentsdescribing these applications include U.S. Pat. Nos. 5,228,531;5,360,648; 5,364,486; 5,721,025; 5,879,768; 5,942,579; and 6,117,465.

Generally for a multilayer film structure, the novel coating methodsapply the coating compositions to the substrate in order to form atleast one layer of the total multilayer film structure. Other layers ofthe multilayer structure may include but are not limited to barrierlayers, and/or tie layers, and/or structural layers.

Various materials can be used for these layers, with some of them beingused as more than one layer in the same film structure. Some of thesematerials include: foil, nylon, ethylene/vinyl alcohol (EVOH)copolymers, polyvinylidene chloride (PVDC), polyethylene terephthalate(PET), polypropylene, oriented polypropylene (OPP), ethylene/vinylacetate (EVA) copolymers, ethylene/acrylic acid (EAA) copolymers,ethylene/methacrylic acid (EMAA) copolymers, LLDPE, HDPE, LDPE, nylon,graft adhesive polymers (for example, maleic anhydride graftedpolyethylene), and paper. Generally, the multilayer film structurescomprise from 2 to 7 layers.

Substrate films can be made by cast extrusion (for monolayer films) orco-extrusion (for multilayer films) by techniques well known in the art.The films can be quenched, irradiated by electron beam irradiation at adosage of between 20 and 35 kiloGrays, and reheated to their orientationtemperature, and then oriented at a ratio of up to 1.5:1, or up to 2:1,or up to 3:1, or up to 4:1, or up to 5:1 in each of the longitudinal(also called machine-direction) and transverse (also calledcross-direction) directions. In one embodiment, the orientation is about5:1 in the traverse direction and about 10:1 in the longitudinaldirection. In another embodiment the orientation is about 7:1 in each ofthe longitudinal and transverse directions.

The substrate films may be made by any suitable process, includingco-extrusion, lamination, extrusion coating, or corona bonding and canbe made by tubular cast co-extrusion, such as that shown in U.S. Pat.No. 4,551,380 (Schoenberg). Bags made from the film can be made by anysuitable process, such as that shown in U.S. Pat. No. 3,741,253 (Brax etal.). Side or end sealed bags may be made from single wound or doublewound films.

Substrate films may be oriented by any suitable process, including atrapped bubble process or a simultaneous or sequential tenter frameprocess. Films may have any total thickness desired, so long as the filmprovides the desired properties for the particular packaging operationin which the films are used. Final film thicknesses may vary, dependingon process, end use application, etc. Typical thicknesses range from 0.1to 20 mils, preferably 0.2 to 15 mils, more preferably 0.3 to 10 mils,more preferably 0.3 to 5 mils, more preferably 0.3 to 2 mils, such as0.3 to 1 mil.

Suitable thermoplastic polymer materials include, but are not limitedto, polyesters, polycarbonates, polyarylates, polyamides, polyimides,polyamide-imides, polyether-amides, polyetherimides, polyaryl ethers,polyarylether ketones, aliphatic polyketones, polyphenylene sulfide,polysulfones, polystyrenes and their derivatives, polyacrylates,polymethacrylates, cellulose derivatives, polyethylenes, polypropylene(preferably homopolymers), other polyolefins, copolymers having apredominant olefin monomer, fluorinated polymers and copolymers,chlorinated polymers, polyacrylonitrile, polyvinylacetate,polyvinylalcohol, polyethers, ionomeric resins, elastomers, siliconeresins, epoxy resins, and polyurethanes. Miscible or immiscible polymerblends comprising any of the above-named polymers, and copolymerscomprising any of the constituent monomers of any of the above-namedpolymers, are also suitable, provided an oriented film may be producedfrom such a blend or copolymer.

As used herein the term “copolymer” and “interpolymer” are usedinterchangeably, to mean polymers formed from two or more monomers.

While reference to specific thermoplastic resins has been made,embodiments of the present invention may be generally used with anysuitable thermoplastic resin. In addition, while reference has been madeto single layers, it is expressly within the scope of the presentinvention that multiple layers may be used. Thus, combinations of layerssuch as those described herein may be used. In addition, however, it isexpressly within the scope of the present invention that other layerswhich may be formed from other materials may be overlaid or interposedbetween layers formed from the dispersions disclosed herein.

Drying Conditions (Step 204)

Once the dispersion is coated onto the desired substrate, the coating isdried to remove the water and to coalesce the polymer particles into asubstantially continuous film. In one embodiment, an oven may be used toaccelerate the drying process. To properly coalesce the polymerparticles, the coating is preferably allowed to reach a temperatureapproximately 20° C. above the melting point of the polymer from whichthe dispersion is produced. As an example, in the case of a dispersionproduced from AFFINITY™ EG 8200 co-polymer (an ethylene/1-octenecopolymer having a 60° C. melting point as determined by DSC at ascanning rate of about 10° C. per minute, available from The DowChemical Company, Midland, Mich.), the coated film should reach atemperature of about 80° C.

In selected embodiments, the temperature range used ranges from the peakmelting point of the polymer base of the dispersion to the softeningpoint of the base film. In certain embodiments, the coated substrate mayexit the drying oven at a temperature from 110° C. above the peakmelting point of the polymer base of the dispersion to 110° C. below thesoftening point of the base film. In other embodiments the substrate mayexit the drying oven at a temperature from 20° C. above the peak meltingpoint of the polymer base of the dispersion to 20° C. below thesoftening point of the base film.

The dispersion coated substrate, as described hereinabove, may be driedvia any conventional drying method. Such conventional drying methodsinclude but, are not limited to, air drying, convection oven drying, hotair drying, microwave oven drying, and/or infrared oven drying. Thedispersion coated substrate may be dried at any temperature; forexample, it may be dried at a temperature in the range of equal orgreater than the melting point temperature of the thermoplastic resin;or in the alternative, it may be dried at a temperature in the range ofless than the melting point of the thermoplastic resin. The dispersioncoated substrate may be dried at a temperature in the range of about 60°F. (15.5° C.) to about 700° F. (371° C.). All individual values andsubranges from about 60° F. (15.5° C.) to about 700° F. (371° C.) areincluded herein and disclosed herein; for example, the dispersion coatedsubstrate may be dried at a temperature in the range of about 60° F.(15.5° C.) to about 500° F. (260° C.), or in the alternative, thedispersion coated substrate may be dried at a temperature in the rangeof about 60° F. (15.5° C.) to about 450° F. (232.2° C.). The temperatureof the dispersion may be raised to a temperature in the range of equalor greater than the melting point temperature of the thermoplastic resinfor a period of less than about 40 minutes. All individual values andsubranges from less than about 40 minutes are included herein anddisclosed herein; for example, the temperature of the dispersion may beraised to a temperature in the range of equal or greater than themelting point temperature of the thermoplastic resin for a period ofless than about 20 minutes, or in the alternative, the temperature ofthe dispersion may be raised to a temperature in the range of equal orgreater than the melting point temperature of the thermoplastic resinfor a period of less than about 5 minutes, or in another alternative,the temperature of the dispersion may be raised to a temperature in therange of equal or greater than the melting point temperature of thethermoplastic resin for a period in the range of about 0.5 to 300seconds. In another alternative, the temperature of the dispersion maybe raised to a temperature in the range of less than the melting pointtemperature of the thermoplastic resin for a period of less than 40minutes. All individual values and subranges from less than about 40minutes are included herein and disclosed herein; for example, thetemperature of the dispersion may be raised to a temperature in therange of less than the melting point temperature of the thermoplasticresin for a period of less than about 20 minutes, or in the alternative,the temperature of the dispersion may be raised to a temperature in therange of less than the melting point temperature of the thermoplasticresin for a period of less than about 5 minutes, or in anotheralternative, the temperature of the dispersion may be raised to atemperature in the range of less than the melting point temperature ofthe thermoplastic resin for a period in the range of about 0.5 to 300seconds.

Drying the dispersion at a temperature in the range of less than themelting point temperature of the thermoplastic resin may be desirablebecause it facilitates the formation of a film having a continuousstabilizing agent phase with a discrete thermoplastic resin phasedispersed therein.

Drying the dispersion at a temperature in the range of equal or greaterthan the melting point temperature of the thermoplastic resin may bedesirable because it facilitates the formation of a film having acontinuous thermoplastic resin phase with a discrete stabilizing agentphase dispersed therein, thereby improving the oil and grease resistanceas well as providing a barrier for moisture and vapor transmission.

EXAMPLES Dispersion Preparation Example 1

100 parts by weight of a thermoplastic ethylene-vinyl acetate copolymercommercially available from DuPont having a vinyl acetate content ofabout 28 weight percent, a density of about 0.95 g/cc (ASTM D-792) and amelt index of about 6 g/10 minute (as determined according to ASTM D1238at 190° C. and 2.16 kg), and a melting point of about 73° C. (asdetermined according to ASTM D3417) and 4.2 parts by weight of a C₃₂carboxylic acid (UNICID 425 manufactured by Baker-Petrolite, acid value97 mg KOH/g) are melt kneaded at 180° C. in a twin screw extruder at arate of 8.3 kg/hr.

Upon the melt kneaded resin/surfactant, 4.6 weight percent aqueoussolution of potassium hydroxide is continuously fed into a downstreaminjection port at a rate 0.9 kg/hr (at a rate of 10 weight percent ofthe total mixture). This aqueous dispersion is subsequently diluted withadditional water at a rate of 5.7 kg/hr before exiting the extruder. Anaqueous dispersion having a solids content of 56 weight percent at pH10.7 is obtained. The dispersed polymer phase measured by a CoulterLS230 particle analyzer consisted of an average volume diameter of 0.56micron and a particle size distribution (Dv/Dn) of 1.45. The term“dispersed polymer phase” simply refers to the thermoplastic resin inthe dispersion.

Dispersion Preparation Example 2

100 parts by weight of a thermoplastic ethylene/1-octene copolymer withan octene content of about 38 weight percent, a density of about 0.87g/cc (ASTM D-792) and a melt index of about 5 g/10 minutes (asdetermined according to ASTM D1238 at 190° C. and 2.16 kg) a Mw/Mn ofabout 2.0, and a melting point of about 63° C. (as determined by DSC ata scanning rate of about 10° C. per minute), commercially available fromThe Dow Chemical Co., Midland, Mich., as ENGAGE 8200, and 3.1 parts byweight of a C₁₈/C₁₆ carboxylic acid (INDUSTRENE 106 manufactured by CKWitco, acid value 200 mg KOH/g) are melt kneaded at 125° C. in a twinscrew extruder at a rate of 7.9 kg/hr.

Upon the melt kneaded resin/surfactant, 23.9 weight percent aqueoussolution of potassium hydroxide is continuously fed into a downstreaminjection port at a rate 0.2 kg/hr (at a rate of 2.5 weight percent ofthe total mixture). This aqueous dispersion is subsequently diluted withadditional water at a rate of 5.4 kg/hr before exiting the extruder. Tofurther dilute the resulting dispersion, additional water is added at arate of 0.7 kg/hr after the mixture exited the extruder. An aqueousdispersion having a solids content of 56 weight percent at pH 9.6 isobtained. The dispersed polymer phase measured by a Coulter LS230particle analyzer consisted of an average volume diameter of 2.04 micronand a particle size distribution (Dv/Dn) of 1.18.

Dispersion Preparation Example 3

100 parts by weight of a thermoplastic ethylene/1-octene copolymer withoctene content of about 38 weight percent, a density of about 0.87 g/cc(ASTM D-792) and a melt index of about 5 g/10 minutes (as determinedaccording to ASTM D1238 at 190° C. and 2.16 kg) a Mw/Mn of about 2.0,and a melting point of about 63° C. (as determined by DSC at a scanningrate of about 10° C. per minute.), commercially available from The DowChemical Co., Midland, Mich., as ENGAGE 8200, and 3.6 parts by weight ofa C₂₂/C₁₈ carboxylic acid (High-erucic rapeseed oil manufactured byMontana Specialty Mills, acid value 97 mg KOH/g) are melt kneaded at150° C. in a twin screw extruder at a rate of 5.0 kg/hr.

Upon the melt kneaded resin/surfactant, 16.3 weight percent aqueoussolution of potassium hydroxide is continuously fed into a downstreaminjection port at a rate 0.1 kg/hr (at a rate of 2.0 weight percent ofthe total mixture). This aqueous dispersion is subsequently diluted withadditional water at a rate of 3.2 kg/hr before exiting the extruder. Tofurther dilute the resulting dispersion, additional water is added at arate of 0.8 kg/hr after the mixture exited the extruder. An aqueousdispersion having a solids content of 55 weight percent at pH 10.7 isobtained. The dispersed polymer phase measured by a Coulter LS230particle analyzer consisted of an average volume diameter of 1.11microns and a particle size distribution (Dv/Dn) of 1.85.

Dispersion Preparation Example 4

100 parts by weight of a thermoplastic ethylene/1-octene copolymer withoctene content of about 38 weight percent, a density of about 0.87 g/cc(ASTM D-792) and a melt index of about 5 g/10 minutes (as determinedaccording to ASTM D1238 at 190° C. and 2.16 kg) a Mw/Mn of about 2.0,and a melting point of about 63° C. (as determined by DSC at a scanningrate of about 10° C. per minute.), commercially available from The DowChemical Co., Midland, Mich., as ENGAGE 8200 and 3.1 parts by weight ofa C₂₆ carboxylic acid (UNICID 350 manufactured by Baker-Petrolite, acidvalue 115 mg KOH/g) are melt kneaded at 150° C. in a twin screw extruderat a rate of 9.7 kg/hr.

Upon the melt kneaded resin/surfactant, 12.5 weight percent aqueoussolution of potassium hydroxide is continuously fed into a downstreaminjection port at a rate 0.2 kg/hr (at a rate of 2.0 weight percent ofthe total mixture). This aqueous dispersion is subsequently diluted withadditional water at a rate of 7.5 kg/hr before exiting the extruder. Anaqueous dispersion having a solids content of 56 weight percent at pH10.8 is obtained. The dispersed polymer phase measured by a CoulterLS230 particle analyzer consisted of an average volume diameter of 0.79micron and a particle size distribution (Dv/Dn) of 1.95.

Dispersion Preparation Example 5

100 parts by weight of a thermoplastic propylene-ethylene copolymer withan ethylene content of about 12.7 weight percent, a density of about0.864 g/cc (ASTM D-792) and a melt flow rate of about 23 g/10 minutes(as determined according to ASTM D1238 at 230° C. and 2.16 kg), amelting point of 60-70° C., a Mw/Mn of about 2.0, and a flexural modulusof about 4 kpsi, and 6.4 parts by weight of a C₂₆ carboxylic acid(UNICID 350 manufactured by Baker-Petrolite, acid value 115 mg KOH/g)are melt kneaded at 150° C. in a twin screw extruder at a rate of 1.6kg/hr.

Upon the melt kneaded resin/surfactant, 25 weight percent aqueoussolution of potassium hydroxide is continuously fed into a downstreaminjection port at a rate 0.08 kg/hr (at a rate of 4.8 weight percent ofthe total mixture). This aqueous dispersion is subsequently diluted withadditional water at a rate of 1.5 kg/hr before exiting the extruder. Anaqueous dispersion having a solids content of 51 weight percent at pH11.6 is obtained. The dispersed polymer phase measured by a CoulterLS230 particle analyzer consisted of an average volume diameter of 0.61micron and a particle size distribution (Dv/Dn) of 1.31.

Dispersion Preparation Example 6

100 parts by weight of a thermoplastic propylene-ethylene copolymer withethylene comonomer content of about 9 weight percent, a melting point of86° C., a melt flow rate of about 25 g/10 minutes (as determinedaccording to ASTM D1238 at 230° C. and 2.16 kg), and a Mw/Mn of about2.0, and 42.9 parts by weight of an ethylene acrylic acid copolymer,available from The Dow Chemical Company under the tradename PRIMACOR™59801, with a melt index of about 15 g/10 minutes determined accordingto ASTM D1238 at 125° C./2.16 kg (which is equivalent to about 300 g/10min when determined according to ASTM D1238 at 190° C./2.16 kg), anacrylic acid content of about 20.5 weight percent, and a DSC meltingpoint of about 77° C. are melt kneaded at 170° C. in a twin screwextruder at a rate of 4.3 kg/hr.

Upon the melt kneaded resin/surfactant, 11.7 weight percent aqueoussolution of potassium hydroxide is continuously fed into a downstreaminjection port at a rate 1.6 kg/hr (at a rate of 27.1 weight percent ofthe total mixture). This aqueous dispersion is subsequently diluted withadditional water at a rate of 2.7 kg/hr before exiting the extruder. Tofurther dilute the resulting dispersion, additional water is added at arate of 2.3 kg/hr after the mixture exited the extruder. An aqueousdispersion having a solids content of 41 weight percent at pH 9.9 isobtained. The dispersed polymer phase measured by a Coulter LS230particle analyzer consisted of an average volume diameter of 0.86 micronand a particle size distribution (Dv/Dn) of 1.48.

As demonstrated above, embodiments of the invention provide new methodsfor making a coated substrate by applying and drying dispersions on thesubstrate, and those coated substrates are useful for many applications.In some instances, the new methods make the coatings using dispersionsthat have one or more of the following advantages. First, some newcoatings made from the dispersions have better durability. Certaincoatings made from the dispersions exhibit improved adhesion propertiesand others may have improved adhesion as well as good toughness anddurability. Other coatings made from the dispersions are easier toprocess in a melt-extrusion process. In particular, some coatings madefrom the dispersions are easier to process due to the low melting pointof the polymers deposited from the dispersions. Some coatings made fromthe dispersions have the feature of being low yellowing. In addition,some coatings have the added benefit of sealing at a lower temperature.Other characteristics and additional advantages are apparent to thoseskilled in the art.

Example 7

AFFINITY™ EG-8200 (an ethylene/1-octene co-polymer having a melt indexof 5 dg/min and a density of 0.87 g/cc, available from The Dow ChemicalCompany) is dispersed, using the method described in U.S. Pat. No.5,539,021 (Pate), which is hereby incorporated by reference in itsentirety, using 4 weight percent sodium dodecylbenzene sulfonate(RHODACAL™ DS-10, available from Rhodia Chemicals) as a dispersing agentand toluene as a solvent. After vacuum stripping, the resultantdispersion has an average volume diameter of 0.80 microns at 46.0percent solids loading.

An untreated (i.e., no corona treatment) LLDPE film made from DOWLEX™2071 polyethylene (an LLDPE having a melt flow of about 1 dg/min and adensity of about 0.92 g/cc, available from The Dow Chemical Company,Midland, Mich.) of 2 mils (50.8 microns) thickness is cut into 12 inchby 6 inch sheets. Each of the sheets is taped to a sheet of glass andcoated using wire-round rods (rod #'s 4, 12, 20, and 28). Table 3 showsthe coat weights of the various samples.

TABLE 3 Coating Weight and Thickness of Dispersion Coated LDPE FilmSamples Coat Coat Gross Wt. Std Dev. Coat Wt. Thickness Thickness Rod#g/m² g/m² g/m² Mils microns Control 45.18 2.22 0.00 0.00 0.00  4 49.001.16 3.82 0.17 4.32 12 57.91 1.41 12.74 0.58 14.73 20 67.19 4.69 22.021.00 25.40 28 72.01 3.12 26.83 1.21 30.73

For each coated weight, individual strips (1 inch wide) having nobacking are heat sealed 45, 50, 55, 60, 65, 70, 75, and 80° C.,respectively, using a Packforsk Hot Tack Tester set at 40 psi sealpressure and 0.5 second dwell time. Sealed samples are allowed toequilibrate for at least a day in a room set at 70° F. (21.1° C.) and 50percent relative humidity before being pulled on Instron model 4501tensile testing device. For this experiment, a seal is declared a “weld”if the seal force is greater than the force (4 lbs. (1.8 kg)) requiredto irreversibly elongate and re-orient the crystal structure within the2 mils (50.8 microns) thick LLDPE films. Results of the experiment areshown in Table 4.

As used herein, the temperature at which a seal strength of 0.5 lb/in isachieved is known as the heat seal initiation temperature. The heat sealinitiation temperature for the coatings in this example set is from 45°C. to 60° C., depending on the coating weight.

TABLE 4 Peel Strength for Ethylene-Octene Copolymer Dispersion CoatedLDPE Films Seal Temp, ° C. Mean Peak Peel Strength, lb/in 45 0.08 0.020.10 0.12 50 0.18 0.20 0.38 0.55 55 0.46 0.53 0.35 1.37 60 1.05 1.482.12 3.46 65 1.14 2.27 3.76 3.20 70 1.16 3.20 3.51 >4 75 1.13 3.083.82 >4 80 — 1.44 >4 >4 Coating Wt., g/m² 3.82 12.7 22.0 26.8

The metric equivalents for the above table is provided in Table 4Mbelow:

TABLE 4M Peel Strength for Ethylene-Octene Copolymer Dispersion CoatedLDPE Films Seal Temp, ° C. Mean Peak Peel Strength, g/cm 45 13 4 18 2150 32 36 68 99 55 83 95 63 244 60 187 264 380 618 65 204 405 671 571 70206 573 627 >700 75 202 551 682 >700 80 — 257 >700 >700 Coating Wt.,g/m² 3.82 12.7 22.0 26.8

Example 8

A sample of propylene-ethylene co-polymer (ethylene content of 12% byweight with a melt flow rate of about 25 g/10 min as determinedaccording to ASTM D1238 at 230° C. with a 2.16 kg weight) is convertedto an aqueous dispersion using a technique as described in co-pendingU.S. Patent Application Publication No. 20050100754. 100 parts by weightof the propylene-ethylene co-polymer and 3.1 parts by weight of a C26carboxylic acid (UNICID 350 manufactured by Baker-Petrolite, acid value115 mg KOH/g) is melt kneaded at 150° C. in twin screw extruder at arate of 6.6 kg/hr.

To the melt kneaded resin/surfactant blend, a 13.5 wt % aqueous solutionof potassium hydroxide is continuously fed into a downstream injectionport at a rate 0.17 kg/hr (which equates to 2.5 wt % of the totalmixture). This aqueous dispersion is subsequently diluted in a two stepprocess with water containing 5.0 weight percent dioctyl sodiumsulfosuccinate (Aerosol OT-100 manufactured by Cytec Industries) at arate of 3.7 kg/hr, and secondly additional water added at a rate of 1.1kg/hr before exiting the extruder. To further dilute the resultingdispersion, additional water is added at a rate of 1.8 kg/hr after themixture exited the extruder. An aqueous dispersion having a solidscontent of 51 wt % at pH 10.2 is obtained. The dispersed polymer phasemeasured by a Coulter LS230 particle analyzer consisted of an averagevolume diameter of 0.64 micron and a particle size distribution (Dv/Dn)of 1.33.

While the polymers discussed here provide good low temperature heat sealinitiation properties, other polymers may also be included in thedispersion to improve other properties. For example, a very low or ultralow density polyethylene, a linear low density polyethylene or highdensity polyethylene could be included in the dispersion to improveother properties. If the oriented substrate is nylon, for example, itmay be advantageous to include a functionalized polymer such as ethyleneacrylic acid or a maleic anhydride grafted polypropylene. Similarly, ifthe oriented substrate is polyester, for example, other functionalizedpolymers such as ethylene vinyl acetate copolymers or ethylene ethylacrylate copolymers may be advantageous to include in the dispersion.

A corona treated BOPP (BICOR LBW, a slip modified, non-heat sealable OPPfilm made by ExxonMobil Chemical Corporation) of 1.2 mils is cut into 12inch by 14 inch sheets. Each of the sheets is taped to a flat foamedplastic board and the dispersion described above is coated onto the BOPP(the side without a slip additive) using wire-round rods (rod #'s 4, 12,and 18). The purpose of the foamed plastic board is to achieve a moreconsistent coating thickness.

Coated sheets are placed into a convection oven at 135° C. for 5 minutesto dry the dispersion coating. The resulting coating thickness isdetermined gravimetrically. Ten pieces (1-inch by 1-inch) of coated filmsamples are weighed individually and the coating thickness is determinedby subtracting the weight of the base BOPP substrate. A density of 0.864g/cc is used for calculating the coating thickness based on the weightdifference. The results are shown in Table 5.

TABLE 5 Coating Weight and Thickness of Dispersion Coated BOPP FilmSamples Coat Coat Gross Wt. Std Dev. Coat Wt. Thickness Thickness Rod#g/m² g/m² g/m² Mils μm Control 27.75 2.84 0.00 0.00 0.00  4 30.85 2.363.10 0.14 3.59 12 40.46 1.54 12.71 0.58 14.71 18 45.57 2.75 17.83 0.8120.64

For each coated weight, individual strips (1 inch wide) having nobacking are heat sealed from 50 to 140° C. in 10° C. increments, using aPackforsk Hot Tack Tester set at 40 psi seal pressure and 0.5 seconddwell time. Sealed samples are allowed to equilibrate for at least a dayin an ASTM room set at 70° F. (21.1° C.) and 50 percent relativehumidity before being pulled on Instron model 4501 tensile testingdevice at a rate of 10 inches per minute. Results of the experiment areshown in Table 6.

As used herein, the temperature at which a seal strength of 0.5 lb/in isachieved is defined as the heat seal initiation temperature. The heatseal initiation temperature for the coating in this example set is fromapproximately 56° C. to 76° C., depending on the coating weight.

TABLE 6 Peel Strength for Propylene-Ethylene Copolymer Dispersion CoatedBOPP Films Seal Temp, ° C. Mean Peak Peel Strength, lb/in 50 0.0 0.310.0 60 0.0 0.77 0.15 70 0.23 2.29 0.62 80 0.63 2.52 2.08 90 0.84 2.322.20 100  0.88 2.33 2.50 120  0.78 1.98 2.81 130  0.92 2.27 2.76 140 0.93 2.58 2.84 Coating Wt., g/m² 3.59 14.71 20.64

Metric equivalents of the above table are provided in Table 6M below:

TABLE 6M Peel Strength for Propylene-Ethylene Copolymer DispersionCoated BOPP Films Seal Temp, ° C. Mean Peak Peel Strength, g/cm 50 0 550 60 0 137 27 70 41 409 110 80 112 451 372 90 150 415 393 100  157 417447 120  140 354 503 130  165 406 493 140  167 461 508 Coating Wt., g/m²3.59 14.71 20.64

Example 9

100 parts by weight of a thermoplastic propylene-ethylene copolymer(with ethylene comonomer content of about 9 weight percent, a meltingpoint of 86° C., a melt flow rate of about 25 g/10 minutes (asdetermined according to ASTM D1238 at 230° C. and 2.16 kg), and a Mw/Mnof about 2.0) and 42.9 parts by weight of an ethylene acrylic acidcopolymer (available from The Dow Chemical Company under the tradenamePRIMACOR™ 59801, with a melt index of about 15 g/10 minutes determinedaccording to ASTM D1238 at 125° C./2.16 kg (which is equivalent to about300 g/10 min when determined according to ASTM D1238 at 190° C./2.16kg), an acrylic acid content of about 20.5 weight percent, and a DSCmelting point of about 77° C.) are melt kneaded at 170° C. in a twinscrew extruder at a rate of 4.3 kg/hr.

Upon the melt kneaded resin/surfactant, 11.7 weight percent aqueoussolution of potassium hydroxide is continuously fed into a downstreaminjection port at a rate 1.6 kg/hr (at a rate of 27.1 weight percent ofthe total mixture). This aqueous dispersion is subsequently diluted withadditional water at a rate of 2.7 kg/hr before exiting the extruder. Tofurther dilute the resulting dispersion, additional water is added at arate of 2.3 kg/hr after the mixture exits the extruder. An aqueousdispersion having a solids content of 41 weight percent at pH 9.9 isobtained. The dispersed polymer phase measured by a coulter LS230particle analyzer consists of an average volume diameter of 0.86 micronand a particle size distribution (Dv/Dn) of 1.48.

An aluminum foil having a thickness of 40 mils (1 mm) is cut into 12inch by 14 inch sheets. Each of the sheets is taped to a flat foamedplastic board and the dispersion described above is coated onto the foilusing a #4 wire-round rod. The purpose of the foamed plastic board is toachieve a more consistent coating thickness.

Coated sheets are placed into a convection oven at 135° C. for 5 minutesto dry the dispersion coating. The resulting coating thickness isdetermined gravimetrically to be 3.5 g/m². To vary the coatingthickness, some of the sheets were coated again using a #4 wire-roundrod and then dried according to conditions above. The resulting coatingthickness is determined gravimetrically to be 6.1 g/m².

For the two coating weights, individual disks 3 inches wide (76 mm) areprepared from the coated sheets above to create a sealable lid. The lidis then heat sealed from 135 to 160° C. with a force of approximately 40psi seal pressure and 1 second dwell time to a thermoformedpolypropylene cup. The cup was thermoformed from a 40 mil (1 mm) sheetof homopolymer polypropylene available from The Dow Chemical Companyunder the product name H110-02N. The sealing surface of the cup has anouter diameter of 3.00 inches (76 mm) and an inner diameter of 2.84inches. (Sealed samples are allowed to equilibrate for at least a day inan ASTM room set at 70° F. (21.1° C.) and 50 percent relative humiditybefore being pulled on Instron model 4501 tensile testing device at arate of 10 inches per minute. Results of the experiment are shown inTable 7.

TABLE 7 Peel Strength for Propylene-Ethylene Copolymer Dispersion CoatedFoil Lid Mean Peak Peel Seal Temp, ° C. Strength, lb/in 135 1.0 2.5 1401.2 2.9 150 1.6 3.6 160 1.7 3.7 Coating Wt., g/m² 3.5 6.1

From the data in Table 7, a peak peel strength of between 1.5 and 2.0lb/in was achieved at a coating weight of 3.5 g/m². This range of peelstrength between 1.5 and 2.0 lb/in is critical for many packagingapplications as this range is typically considered peelable by having agood balance of seal strength for package integrity yet can be easilyopened by most consumers.

Example 10

100 parts by weight of a thermoplastic ethylene/1-octene copolymer withoctene content of about 38 weight percent, a density of about 0.87 g/cc(ASTM D-792) and a melt index of about 5 g/10 minutes (as determinedaccording to ASTM D1238 at 190° C. and 2.16 kg) a Mw/Mn of about 2.0,and a melting point of about 63° C. (as determined by DSC at a scanningrate of about 10° C. per minute.), commercially available from The DowChemical Co., Midland, Mich., and 3.1 parts by weight of a C₂₆carboxylic acid (UNICID 350 manufactured by Baker-Petrolite, acid value115 mg KOH/g) are melt kneaded at 150° C. in a twin screw extruder at arate of 9.7 kg/hr.

Upon the melt kneaded resin/surfactant, 12.5 weight percent aqueoussolution of potassium hydroxide is continuously fed into a downstreaminjection port at a rate 0.2 kg/hr (at a rate of 2.0 weight percent ofthe total mixture). This aqueous dispersion is subsequently diluted withadditional water at a rate of 7.5 kg/hr before exiting the extruder. Anaqueous dispersion having a solids content of 56 weight percent at pH10.8 is obtained. The dispersed polymer phase measured by a CoulterLS230 particle analyzer consisted of an average volume diameter of 0.79micron and a particle size distribution (Dv/Dn) of 1.95.

Glass sheets, similar to those used to coat the film in Example 1, arecoated with the above described dispersion using wire-wound rods (rod#'s 4, 12, 20, and 28). The dispersions are then allowed to dry,resulting in a thin film layer on the glass sheets.

As described above, at the low coating thickness (#4 rod), the resultingthin film layer may be essentially transparent. The film layer maybecome translucent at higher coating thicknesses.

Example 11

As described above, substrates may advantageously be coated with two ormore dispersion layers to result in desired properties, such as adesired adhesion (peel strength) or seal temperature. In someembodiments the dispersion layers may be dried sequentially, and inother embodiments, the dispersion layers may be dried simultaneously.

For example, a nylon or polyethylene terephthalate film may be coatedwith a first dispersion including an ethylene-vinyl acetate copolymer. Asecond dispersion may then be applied to the substrate, such as anethylene-based copolymer having a low melting temperature, resulting ina substrate having a low heat seal temperature and good adhesion betweenthe substrate and the coating layers.

Similarly, other substrates, including metals, wood, paper, glass, andothers as described above, may include two or more coating layers. Inthis manner, the properties of the coating may be tailored to both thesubstrate and the end use, minimizing polymer incompatibility issues andother similar problems.

Thus, dispersions in accordance with embodiments disclosed herein may beused to coat substrates. In particular, embodiments may provide a film(obtained from the coated substrate), which may have a heat sealinitiation temperature between about 45° C. and 90° C. In otherembodiments the heat seal initiation temperatures may range from 65° C.to 80° C., 70° C. to 75° C., or 70° C. to 80° C. Those of ordinary skillin the art will recognize that other values within the range may beincluded.

In selected embodiments, the propylene-based and ethylene-basedcopolymers may be selected to deliver the desired performanceproperties. For example, the heat seal initiation temperature and theheat seal range will be a function of the propylene copolymer selected.Copolymers with higher comonomer content will generally have lower heatseal initiation temperatures.

Those of ordinary skill in the art will also recognize that embodimentsof the dispersions disclosed herein may be applied in a non-uniform orlocalized manner depending on the application. For example, a coatingmay be applied only to a portion (e.g., a strip or band at one end) of asubstrate that is needed to be sealed.

While the polymers discussed herein provide good low temperature heatseal initiation properties, other polymers may also be included in thedispersion to improve other properties. For example, a small amount of ahomopolymer polypropylene or a random copolymer polypropylene may beadded to the dispersion to improve heat resistance or to extend hot tackstrength at higher temperatures. In some embodiments, it may beadvantageous to include a functionalized polymer such as ethyleneacrylic acid or a maleic anhydride grafted polypropylene. Similarly,other functionalized polymers such as ethylene vinyl acetate copolymersor ethylene ethyl acrylate copolymers may be advantageous to include inthe dispersion.

Advantageously, one or more embodiments disclosed herein may provideheat sealable films that may allow for higher packaging line speeds (dueto lower heat seal initiation temperatures), provide the ability to sealpackages over broad operating windows, and provide good packageintegrity.

In other words, one or more embodiments may provide the ability to sealpackages over a broad operating window. During startup and shutdown ofpackaging lines, the temperature of the sealing equipment can oftendeviate, sometimes by a large amount, from the set point. With apackaging film having a low heat seal initiation temperature, anadequate seal can still be generated if the sealing equipment issomewhat cooler than desired.

Advantageously, one or more embodiments disclosed herein may providecoatings for substrates such as polymers, paper, wood, metals,fiberglass, fibers, and non-woven fabrics, where metals may includealuminum, steel, copper, and brass, among others. Coatings obtained fromsome dispersions described herein may exhibit excellent moistureresistance, water repellency, thermal adhesion to paper, water and/orgrease barrier and ink adhesion coatings layers, thermal transferproperties, abrasion resistance, impact resistance, weatherability,solvent resistance, flexibility, and adaptability to high-frequencyfabricating.

While the invention has been described with respect to a limited numberof embodiments, the specific features of one embodiment should not beattributed to other embodiments of the invention. No single embodimentis representative of all aspects of the inventions. Moreover, variationsand modifications therefrom exist. For example, the dispersionsdescribed herein may comprise other components. Various additives mayalso be used to further enhance one or more properties. In someembodiments, the dispersions are substantially free of any additive notspecifically enumerated herein. Some embodiments of the dispersionsdescribed herein consist of or consist essentially of the enumeratedcomponents. In addition, some embodiments of the methods describedherein consist of or consist essentially of the enumerated steps. Theappended claims intend to cover all such variations and modifications asfalling within the scope of the invention.

1. An aqueous dispersion comprising (A) at least one or moreinterpolymers of ethylene with at least one comonomer selected from thegroup consisting of a C₄-C₂₀ linear, branched or cyclic diene, and acompound represented by the formula H₂C═CHR wherein R is a C₂-C₂₀linear, branched or cyclic alkyl group or a C₆-C₂₀ aryl group forming adispersed polymer phase; (B) at least one dispersing agent; and (C)water; wherein the dispersion has a pH of less than 12; wherein thedispersed polymer phase has a volume average particle size of less than5 microns.
 2. The dispersion according to claim 1, wherein thedispersing agent comprises at least one carboxylic acid, at least onesalt of at least one carboxylic acid, at least one carboxylic acidester, or at least one salt of at least one carboxylic acid ester. 3.The dispersion of claim 1, wherein the dispersion has a particle sizedistribution defined as volume average particle diameter (Dv) divided bynumber average particle diameter (Dn) of less than or equal to 2.0.
 4. Afilm layer comprising: a substrate having a coating, wherein the coatingwas obtained from: an aqueous dispersion comprising (A) at least one ormore interpolymers of ethylene with at least one comonomer selected fromthe group consisting of a C₄-C₂₀ linear, branched or cyclic diene, and acompound represented by the formula H₂C═CHR wherein R is a C₂-C₂₀linear, branched or cyclic alkyl group or a C₆-C₂₀ aryl group forming adispersed polymer phase; (B) at least one dispersing agent; and (C)water; wherein the dispersion had a pH of less than 12, and wherein thedispersed polymer phase has a volume average particle size of less than5 microns.
 5. The film layer of claim 4, wherein the coating is heatsealable.
 6. The film layer of claim 4, wherein the substrate comprisesat least one thermoplastic polymer selected from the group consisting ofpolyethylene terephthalate, polyethylene, polycarbonate, polyimide,polyamide, polyphenylene sulfide, polysulfone, aromatic polyester,polyether ether ketone, polyether sulfone, and polyether imide.
 7. Thefilm layer of claim 4, wherein the substrate comprises at least one ofaluminum, glass, copper, brass, and steel.
 8. The film layer of claim 4,wherein the interpolymer of ethylene has a density of less than 0.92g/cc.
 9. The film layer of claim 4, wherein the dispersing agentcomprises at least one carboxylic acid, at least one salt of at leastone carboxylic acid, at least one carboxylic acid ester, or at least onesalt of at least one carboxylic acid ester.
 10. An article comprising: asubstrate having a coating, wherein the coating was obtained from: anaqueous dispersion comprising (A) at least one or more interpolymers ofethylene with at least one comonomer selected from the group consistingof a C₄-C₂₀ linear, branched or cyclic diene, and a compound representedby the formula H₂C═CHR wherein R is a C₂-C₂₀ linear, branched or cyclicalkyl group or a C₆-C₂₀ aryl group forming a dispersed polymer phase of;(B) at least one dispersing agent; and (C) water; wherein the dispersionhad a pH of less than 12, and wherein the dispersed polymer phase has avolume average particle size of less than 5 microns.
 11. The article ofclaim 10, wherein the substrate is selected from the group consisting ofglass paper, wall paper, fiber, fabric, carpet, wood, metal, or aplastic molded article.
 12. The article of claim 10, wherein thedispersing agent comprises at least one carboxylic acid, at least onesalt of at least one carboxylic acid, at least one carboxylic acidester, or at least one salt of at least one carboxylic acid ester. 13.The article of claim 10, wherein the dispersion had a particle sizedistribution defined as volume average particle diameter (Dv) divided bynumber average particle diameter (Dn) of less than or equal to 2.0. 14.The article of claim 10, wherein the dispersion was dried at atemperature in the range of less than a melting temperature of the oneor more interpolymers of ethylene with at least one comonomer selectedfrom the group consisting of a C₄-C₂₀ linear, branched or cyclic diene,and a compound represented by the formula H₂C═CHR wherein R is a C₂-C₂₀linear, branched or cyclic alkyl group or a C₆-C₂₀ aryl group.
 15. Thearticle of claim 10, wherein the dispersion was dried at a temperaturein the range of equal to or greater than a melting temperature of theone or more interpolymers of ethylene with at least one comonomerselected from the group consisting of a C₄-C₂₀ linear, branched orcyclic diene, and a compound represented by the formula H₂C═CHR whereinR is a C₂-C₂₀ linear, branched or cyclic alkyl group or a C₆-C₂₀ arylgroup.
 16. The article of claim 10, wherein the article comprises atleast two coating layers obtained from: an aqueous dispersion comprising(A) at least one or more interpolymers of ethylene with at least onecomonomer selected from the group consisting of a C₄-C₂₀ linear,branched or cyclic diene, and a compound represented by the formulaH₂C═CHR wherein R is a C₂-C₂₀ linear, branched or cyclic alkyl group ora C₆-C₂₀ aryl group; (B) at least one dispersing agent; and (C) water;wherein the dispersion had a pH of less than 12, and wherein thedispersed polymer phase has a volume average particle size of less than5 microns.